chore: optimize HikariCP pool and JVM memory for Raspberry Pi

.env.example

@@ -1,6 +1,13 @@
+SPRING_PROFILES_ACTIVE=dev
+
+APP_ENCRYPTION_SECRET=123456789
+APP_ALLOWED_ORIGINS=http://localhost:8080
+
 DB_NAME=EXAMPLE_DB
 DB_USER=EXAMPLE
 DB_PASSWORD=SECRET
 DB_HOST=127.0.0.1
 DB_PORT=5432
-SPRING_PROFILES_ACTIVE=dev
+
+GMAIL_OAUTH_CLIENT_ID=11111111111-1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a1a.apps.googleusercontent.com
+GMAIL_OAUTH_CLIENT_SECRET=AAAAAA-1a1a1a1a1a1a1_A1a1_A1A1A1A1A

.gitignore

@@ -3,6 +3,7 @@
 *.db
 target
 logs
+tokens
 .env
 
 Icon?

Dockerfile

@@ -6,5 +6,8 @@ RUN mvn clean package -DskipTests
 FROM openjdk:21-jdk
 WORKDIR /app
 COPY --from=build /app/bootstrap/target/*.jar app.jar
+
 EXPOSE 8080
-ENTRYPOINT ["java","-jar","app.jar"]
+EXPOSE 5005
+
+ENTRYPOINT ["java", "-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005", "-Xmx512m", "-Xms256m", "-jar", "app.jar"]

application/pom.xml

@@ -16,5 +16,32 @@
             <groupId>jakarta.validation</groupId>
             <artifactId>jakarta.validation-api</artifactId>
         </dependency>
+
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>2.0.13</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.10.0</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>5.14.2</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.24.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
 </project>

application/src/main/java/com/pablotj/restemailbridge/application/port/EmailConfigurationPort.java

@@ -1,5 +0,0 @@
-package com.pablotj.restemailbridge.application.port;
-
-public interface EmailConfigurationPort {
-    String getDefaultRecipient();
-}

application/src/main/java/com/pablotj/restemailbridge/application/port/in/EmailDefaultConfigPort.java

@@ -0,0 +1,5 @@
+package com.pablotj.restemailbridge.application.port.in;
+
+public interface EmailDefaultConfigPort {
+    String getDefaultRecipient();
+}

application/src/main/java/com/pablotj/restemailbridge/application/port/out/EmailPort.java

@@ -1,8 +1,8 @@
-package com.pablotj.restemailbridge.domain.service;
+package com.pablotj.restemailbridge.application.port.out;
 
 import com.pablotj.restemailbridge.domain.model.Email;
 
-public interface EmailService {
+public interface EmailPort {
 
     Email sendEmail(Email email);
 }

application/src/main/java/com/pablotj/restemailbridge/application/usecase/SendEmailUseCase.java

@@ -1,32 +1,58 @@
 package com.pablotj.restemailbridge.application.usecase;
 
 import com.pablotj.restemailbridge.application.dto.EmailDTO;
-import com.pablotj.restemailbridge.application.port.EmailConfigurationPort;
+import com.pablotj.restemailbridge.application.port.in.EmailDefaultConfigPort;
+import com.pablotj.restemailbridge.application.port.out.EmailPort;
 import com.pablotj.restemailbridge.domain.model.Email;
 import com.pablotj.restemailbridge.domain.repository.EmailRepository;
-import com.pablotj.restemailbridge.domain.service.EmailService;
+import com.pablotj.restemailbridge.domain.service.EmailValidatorService;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
+/**
+ * Use case for sending emails.
+ * <p>
+ * Retrieves the default recipient from EmailDefaultConfigPort, sends the email using EmailPort,
+ * and persists it via EmailRepository.
+ */
 public class SendEmailUseCase {
-    private final EmailConfigurationPort emailConfigurationPort;
-    private final EmailService emailService;
+
+    private static final Logger log = LoggerFactory.getLogger(SendEmailUseCase.class);
+
+    private final EmailValidatorService emailValidatorService;
+    private final EmailDefaultConfigPort emailConfigurationPort;
+    private final EmailPort emailService;
     private final EmailRepository emailRepository;
 
-    public SendEmailUseCase(EmailConfigurationPort emailConfigurationPort, EmailService emailService, EmailRepository emailRepository) {
+    public SendEmailUseCase(EmailValidatorService emailValidatorService, EmailDefaultConfigPort emailConfigurationPort, EmailPort emailService, EmailRepository emailRepository) {
+        this.emailValidatorService = emailValidatorService;
         this.emailConfigurationPort = emailConfigurationPort;
         this.emailService = emailService;
         this.emailRepository = emailRepository;
     }
 
+    /**
+     * Handles sending an email based on the provided DTO.
+     *
+     * @param emailDTO DTO containing from, subject, and body
+     */
     public void handle(EmailDTO emailDTO) {
         String to = emailConfigurationPort.getDefaultRecipient();
-        Email email = emailService.sendEmail(
-                Email.builder()
-                        .from(emailDTO.from())
-                        .to(to)
-                        .subject(emailDTO.subject())
-                        .body(emailDTO.body())
-                        .build()
-        );
+
+        Email email = Email.create(emailDTO.from(), to, emailDTO.subject(), emailDTO.body());
+
+        emailValidatorService.validate(email);
+
+        log.info("Sending email from {} to {}", emailDTO.from(), to);
+
+        try {
+            email = emailService.sendEmail(email);
+            email.markAsSent();
+        } catch (Exception e) {
+            log.error("Error sending email", e);
+            email.markAsFailed(e.getMessage());
+        }
         emailRepository.save(email);
+        log.info("Email successfully sent and persisted to repository for recipient {}", to);
     }
 }

application/src/test/java/com/pablotj/restemailbridge/application/usecase/SendEmailUseCaseTest.java

@@ -0,0 +1,129 @@
+package com.pablotj.restemailbridge.application.usecase;
+
+import com.pablotj.restemailbridge.application.dto.EmailDTO;
+import com.pablotj.restemailbridge.application.port.in.EmailDefaultConfigPort;
+import com.pablotj.restemailbridge.application.port.out.EmailPort;
+import com.pablotj.restemailbridge.domain.model.Email;
+import com.pablotj.restemailbridge.domain.model.EmailStatus;
+import com.pablotj.restemailbridge.domain.repository.EmailRepository;
+import com.pablotj.restemailbridge.domain.service.EmailValidatorService;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.AssertionsForClassTypes.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.argThat;
+import static org.mockito.Mockito.doThrow;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+class SendEmailUseCaseTest {
+
+    private EmailValidatorService emailValidatorService;
+    private EmailPort emailPort;
+    private EmailRepository emailRepository;
+
+    private SendEmailUseCase useCase;
+
+    @BeforeEach
+    void setUp() {
+        EmailDefaultConfigPort emailDefaultConfigPort = mock(EmailDefaultConfigPort.class);
+
+        emailValidatorService = mock(EmailValidatorService.class);
+        emailPort = mock(EmailPort.class);
+        emailRepository = mock(EmailRepository.class);
+
+        useCase = new SendEmailUseCase(
+                emailValidatorService,
+                emailDefaultConfigPort,
+                emailPort,
+                emailRepository
+        );
+
+        when(emailDefaultConfigPort.getDefaultRecipient()).thenReturn("default@example.com");
+    }
+
+    @Test
+    void shouldSendEmailSuccessfully() {
+        // given
+        EmailDTO dto = new EmailDTO("sender@example.com", "Subject", "Body");
+        when(emailPort.sendEmail(any(Email.class)))
+                .thenAnswer(invocation -> invocation.getArgument(0));
+
+        // when
+        useCase.handle(dto);
+
+        // then
+        verify(emailValidatorService).validate(any(Email.class));
+        verify(emailPort).sendEmail(any(Email.class));
+        verify(emailRepository).save(argThat(email ->
+                email.getStatus() == EmailStatus.SENT
+        ));
+    }
+
+    @Test
+    void shouldMarkEmailAsFailedWhenSendThrowsException() {
+        // given
+        EmailDTO dto = new EmailDTO("sender@example.com", "Subject", "Body");
+        when(emailPort.sendEmail(any(Email.class))).thenThrow(new RuntimeException("SMTP error"));
+
+        // when
+        useCase.handle(dto);
+
+        // then
+        verify(emailValidatorService).validate(any(Email.class));
+        verify(emailRepository).save(argThat(email ->
+                email.getStatus() == EmailStatus.FAILED &&
+                        email.getErrorDescription().contains("SMTP error")
+        ));
+    }
+
+    @Test
+    void shouldUseDefaultRecipientFromConfigPort() {
+        // given
+        EmailDTO dto = new EmailDTO("sender@example.com", "Subject", "Body");
+
+        when(emailPort.sendEmail(any(Email.class)))
+                .thenAnswer(invocation -> invocation.getArgument(0));
+
+        // when
+        useCase.handle(dto);
+
+        // then
+        verify(emailRepository).save(argThat(email ->
+                email.getTo().equals("default@example.com")
+        ));
+    }
+
+    @Test
+    void shouldPropagateExceptionWhenValidatorFails() {
+        // given
+        EmailDTO dto = new EmailDTO("sender@example.com", "Subject", "Body");
+
+        doThrow(new RuntimeException("Invalid email")).when(emailValidatorService).validate(any());
+
+        // when & then
+        RuntimeException ex = assertThrows(RuntimeException.class, () -> useCase.handle(dto));
+        assertThat(ex.getMessage()).isEqualTo("Invalid email");
+
+        // El repositorio no debería guardar el email, porque la validación falló antes
+        verify(emailRepository, never()).save(any());
+    }
+
+    @Test
+    void shouldFailWhenEmailDTOHasNullFields() {
+        // given
+        EmailDTO dto = new EmailDTO(null, null, null);
+
+        doThrow(new IllegalArgumentException("Invalid fields")).when(emailValidatorService).validate(any());
+
+        // when & then
+        IllegalArgumentException ex = assertThrows(IllegalArgumentException.class, () -> useCase.handle(dto));
+        assertThat(ex.getMessage()).isEqualTo("Invalid fields");
+
+        verify(emailRepository, never()).save(any());
+    }
+}

bootstrap/pom.xml

@@ -26,17 +26,22 @@
             <scope>runtime</scope>
         </dependency>
 
-        <!-- Swagger/OpenAPI -->
         <dependency>
-            <groupId>org.springdoc</groupId>
-            <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
-            <version>${springdoc.version}</version>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>2.0.13</version>
         </dependency>
 
         <!-- Actuator -->
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-actuator</artifactId>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.springframework.boot</groupId>
+                    <artifactId>spring-boot-starter-logging</artifactId>
+                </exclusion>
+            </exclusions>
         </dependency>
 
         <!-- Test -->

bootstrap/src/main/java/com/pablotj/restemailbridge/bootstrap/EnvironmentValidatorInitializer.java

@@ -0,0 +1,29 @@
+package com.pablotj.restemailbridge.bootstrap;
+
+import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.ConfigurableApplicationContext;
+
+public class EnvironmentValidatorInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> {
+
+    @Override
+    public void initialize(ConfigurableApplicationContext ctx) {
+        String[] requiredProperties = {
+                "APP_ENCRYPTION_SECRET",
+                "APP_ALLOWED_ORIGINS",
+                "DB_NAME",
+                "DB_USER",
+                "DB_PASSWORD",
+                "DB_HOST",
+                "DB_PORT",
+                "GMAIL_OAUTH_CLIENT_ID",
+                "GMAIL_OAUTH_CLIENT_SECRET"
+        };
+
+        for (String prop : requiredProperties) {
+            String value = ctx.getEnvironment().getProperty(prop);
+            if (value == null || value.isEmpty()) {
+                throw new IllegalStateException("ERROR: Property '" + prop + "' is not defined or empty");
+            }
+        }
+    }
+}

bootstrap/src/main/java/com/pablotj/restemailbridge/bootstrap/RestEmailBridgeApplication.java

@@ -11,6 +11,8 @@ import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
 public class RestEmailBridgeApplication {
 
     public static void main(String[] args) {
-        SpringApplication.run(RestEmailBridgeApplication.class, args);
+        SpringApplication app = new SpringApplication(RestEmailBridgeApplication.class);
+        app.addInitializers(new EnvironmentValidatorInitializer());
+        app.run(args);
     }
 }

bootstrap/src/main/resources/application.yml

@@ -1,6 +1,19 @@
 info:
   app:
     version: @project.version@
+
+app:
+  encryption:
+    secret:  ${APP_ENCRYPTION_SECRET}
+  cors:
+    allowed-origins: ${APP_ALLOWED_ORIGINS:http://localhost:8080}
+
+server:
+  port: 8080
+  servlet:
+    context-path: /api
+  forward-headers-strategy: framework
+
 spring:
   application:
     name: restemailbridge
@@ -8,6 +21,18 @@ spring:
     resources:
       add-mappings: false
 
+  datasource:
+    url: jdbc:postgresql://${DB_HOST:localhost}:${DB_PORT:5432}/${DB_NAME:default_db}
+    username: ${DB_USER:postgres}
+    password: ${DB_PASSWORD:postgres}
+    driver-class-name: org.postgresql.Driver
+    hikari:
+      maximum-pool-size: 3
+      minimum-idle: 1
+      idle-timeout: 30000
+      connection-timeout: 10000
+      leak-detection-threshold: 10000
+
   jpa:
     hibernate:
       ddl-auto: validate
@@ -15,6 +40,7 @@ spring:
       hibernate.transaction.jta.platform: org.hibernate.engine.transaction.jta.platform.internal.NoJtaPlatform
       hibernate:
         format_sql: true
+        dialect: org.hibernate.dialect.PostgreSQLDialect
     show-sql: true
 
   jackson:
@@ -26,26 +52,10 @@ springdoc:
     path: /v3/api-docs
   swagger-ui:
     path: /swagger-ui
+  show-actuator: true
 
-server:
-  port: 8080
-  servlet:
-    context-path: /api
-  forward-headers-strategy: framework
-
----
-
-spring:
-  config:
-    activate:
-      on-profile: default
-
-  datasource:
-    url: jdbc:postgresql://${DB_HOST:localhost}:${DB_PORT:5432}/${DB_NAME:default_db}
-    username: ${DB_USER:postgres}
-    password: ${DB_PASSWORD:postgres}
-    driver-class-name: org.postgresql.Driver
-  jpa:
-    properties:
-      hibernate:
-        dialect: org.hibernate.dialect.PostgreSQLDialect
+gmail:
+  oauth2:
+    clientId: ${GMAIL_OAUTH_CLIENT_ID}
+    clientSecret: ${GMAIL_OAUTH_CLIENT_SECRET}
+    redirectUri: http://localhost:8888/Callback

docker-compose.yml

@@ -3,6 +3,8 @@ services:
     build: .
     ports:
       - "8080:8080"
+      - "5005:5005"
+      - "8888:8888"
     depends_on:
       - db
     environment:
@@ -11,8 +13,15 @@ services:
       DB_PORT: ${DB_PORT}
       DB_USER: ${DB_USER}
       DB_PASSWORD: ${DB_PASSWORD}
+      APP_ENCRYPTION_SECRET: ${APP_ENCRYPTION_SECRET}
+      APP_ALLOWED_ORIGINS: ${APP_ALLOWED_ORIGINS}
+      GMAIL_OAUTH_CLIENT_ID: ${GMAIL_OAUTH_CLIENT_ID}
+      GMAIL_OAUTH_CLIENT_SECRET: ${GMAIL_OAUTH_CLIENT_SECRET}
     networks:
       - network
+    volumes:
+      - ./tokens:/app/tokens
+      - ./logs:/app/logs
   db:
     image: postgres:15
     ports:

domain/pom.xml

@@ -16,5 +16,38 @@
             <groupId>jakarta.validation</groupId>
             <artifactId>jakarta.validation-api</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.slf4j</groupId>
+            <artifactId>slf4j-api</artifactId>
+            <version>2.0.13</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter</artifactId>
+            <version>5.10.0</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>5.14.2</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>3.24.2</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
+    <repositories>
+        <repository>
+            <id>maven_central</id>
+            <name>Maven Central</name>
+            <url>https://repo.maven.apache.org/maven2/</url>
+        </repository>
+    </repositories>
 </project>

domain/src/main/java/com/pablotj/restemailbridge/domain/model/Email.java

@@ -1,5 +1,6 @@
 package com.pablotj.restemailbridge.domain.model;
 
+import java.time.Instant;
 import lombok.Builder;
 import lombok.Getter;
 
@@ -7,9 +8,30 @@ import lombok.Getter;
 @Builder
 public class Email {
 
-    private String from;
-    private String to;
-    private String subject;
-    private String body;
+    private final String from;
+    private final String to;
+    private final String subject;
+    private final String body;
+    private EmailStatus status;
+    private final Instant createdAt;
+    private String errorDescription;
 
+    public void markAsSent() {
+        this.status = EmailStatus.SENT;
+    }
+
+    public void markAsFailed(String errorDescription) {
+        this.status = EmailStatus.FAILED;
+        this.errorDescription = errorDescription;
+    }
+
+    public static Email create(String from, String to, String subject, String body) {
+        return Email.builder()
+                .from(from)
+                .to(to)
+                .subject(subject)
+                .body(body)
+                .status(EmailStatus.PENDING)
+                .build();
+    }
 }

domain/src/main/java/com/pablotj/restemailbridge/domain/model/EmailStatus.java

@@ -0,0 +1,5 @@
+package com.pablotj.restemailbridge.domain.model;
+
+public enum EmailStatus {
+    SENT, FAILED, PENDING
+}

domain/src/main/java/com/pablotj/restemailbridge/domain/service/EmailValidatorService.java

@@ -0,0 +1,22 @@
+package com.pablotj.restemailbridge.domain.service;
+
+import com.pablotj.restemailbridge.domain.model.Email;
+
+
+public class EmailValidatorService {
+
+    /**
+     * Validates business rules for Email.
+     */
+    public void validate(Email email) {
+        if (email == null) throw new IllegalArgumentException("Email cannot be null");
+        if (email.getTo() == null || !email.getTo().matches(".+@.+\\..+"))
+            throw new IllegalArgumentException("Recipient email is invalid");
+        if (email.getFrom() == null || email.getFrom().isBlank())
+            throw new IllegalArgumentException("Sender email is required");
+        if (email.getSubject() == null || email.getSubject().isBlank())
+            throw new IllegalArgumentException("Subject is required");
+        if (email.getBody() == null || email.getBody().isBlank())
+            throw new IllegalArgumentException("Body is required");
+    }
+}

domain/src/test/java/com/pablotj/restemailbridge/domain/service/EmailValidatorServiceTest.java

@@ -0,0 +1,62 @@
+package com.pablotj.restemailbridge.domain.service;
+
+import com.pablotj.restemailbridge.domain.model.Email;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+class EmailValidatorServiceTest {
+
+    private final EmailValidatorService validator = new EmailValidatorService();
+
+    @Test
+    void shouldThrowIfEmailIsNull() {
+        assertThatThrownBy(() -> validator.validate(null))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessage("Email cannot be null");
+    }
+
+    @Test
+    void shouldThrowIfRecipientInvalid() {
+        Email email = Email.create("sender@example.com", "not-an-email", "Subject", "Body");
+
+        assertThatThrownBy(() -> validator.validate(email))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessage("Recipient email is invalid");
+    }
+
+    @Test
+    void shouldThrowIfSenderIsBlank() {
+        Email email = Email.create("", "recipient@example.com", "Subject", "Body");
+
+        assertThatThrownBy(() -> validator.validate(email))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessage("Sender email is required");
+    }
+
+    @Test
+    void shouldThrowIfSubjectIsBlank() {
+        Email email = Email.create("sender@example.com", "recipient@example.com", "", "Body");
+
+        assertThatThrownBy(() -> validator.validate(email))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessage("Subject is required");
+    }
+
+    @Test
+    void shouldThrowIfBodyIsBlank() {
+        Email email = Email.create("sender@example.com", "recipient@example.com", "Subject", "");
+
+        assertThatThrownBy(() -> validator.validate(email))
+                .isInstanceOf(IllegalArgumentException.class)
+                .hasMessage("Body is required");
+    }
+
+    @Test
+    void shouldPassForValidEmail() {
+        Email email = Email.create("sender@example.com", "recipient@example.com", "Subject", "Body");
+
+        // no debe lanzar excepción
+        validator.validate(email);
+    }
+}

infrastructure/pom.xml

@@ -23,6 +23,22 @@
         <dependency>
             <groupId>org.springframework.boot</groupId>
             <artifactId>spring-boot-starter-web</artifactId>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.springframework.boot</groupId>
+                    <artifactId>spring-boot-starter-logging</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-mail</artifactId>
+            <exclusions>
+                <exclusion>
+                    <groupId>org.springframework.boot</groupId>
+                    <artifactId>spring-boot-starter-logging</artifactId>
+                </exclusion>
+            </exclusions>
         </dependency>
         <dependency>
             <groupId>org.springframework.boot</groupId>
@@ -33,12 +49,99 @@
             <artifactId>spring-boot-starter-validation</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-security</artifactId>
+        </dependency>
+        
         <dependency>
             <groupId>org.reflections</groupId>
             <artifactId>reflections</artifactId>
             <version>0.10.2</version>
         </dependency>
 
+        <dependency>
+            <groupId>com.google.http-client</groupId>
+            <artifactId>google-http-client-jackson2</artifactId>
+            <version>1.43.0</version>
+        </dependency>
+
+        <!-- https://mvnrepository.com/artifact/com.google.api-client/google-api-client -->
+        <dependency>
+            <groupId>com.google.api-client</groupId>
+            <artifactId>google-api-client</artifactId>
+            <version>1.35.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.google.oauth-client</groupId>
+            <artifactId>google-oauth-client-jetty</artifactId>
+            <version>1.39.0</version>
+        </dependency>
+
+
+        <!-- Swagger/OpenAPI -->
+        <dependency>
+            <groupId>org.springdoc</groupId>
+            <artifactId>springdoc-openapi-starter-webmvc-ui</artifactId>
+            <version>${springdoc.version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.google.apis</groupId>
+            <artifactId>google-api-services-gmail</artifactId>
+            <version>v1-rev110-1.25.0</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpclient</artifactId>
+            <version>4.5.13</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>commons-logging</groupId>
+                    <artifactId>commons-logging</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+
+        <dependency>
+            <groupId>javax.mail</groupId>
+            <artifactId>javax.mail-api</artifactId>
+            <version>1.6.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.sun.mail</groupId>
+            <artifactId>jakarta.mail</artifactId>
+            <version>2.0.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.sun.activation</groupId>
+            <artifactId>jakarta.activation</artifactId>
+            <version>2.0.1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-core</artifactId>
+            <version>2.24.1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-slf4j2-impl</artifactId>
+            <version>2.24.1</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.logging.log4j</groupId>
+            <artifactId>log4j-api</artifactId>
+            <version>2.24.1</version>
+        </dependency>
+
+
         <!-- MapStruct -->
         <dependency>
             <groupId>org.mapstruct</groupId>
@@ -51,5 +154,30 @@
             <artifactId>lombok</artifactId>
             <optional>true</optional>
         </dependency>
+
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
+    <repositories>
+        <repository>
+            <id>maven_central</id>
+            <name>Maven Central</name>
+            <url>https://repo.maven.apache.org/maven2/</url>
+        </repository>
+    </repositories>
 </project>

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/CorsConfig.java

@@ -0,0 +1,35 @@
+package com.pablotj.restemailbridge.infrastructure.config;
+
+import java.util.Arrays;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.cors.CorsConfiguration;
+import org.springframework.web.cors.CorsConfigurationSource;
+import org.springframework.web.cors.UrlBasedCorsConfigurationSource;
+
+import java.util.List;
+
+@Configuration
+public class CorsConfig {
+
+    @Value("${app.cors.allowed-origins}")
+    private String allowedOriginsString;
+
+    @Bean
+    public CorsConfigurationSource corsConfigurationSource() {
+        CorsConfiguration config = new CorsConfiguration();
+
+        List<String> allowedOrigins = Arrays.asList(allowedOriginsString.split(","));
+        config.setAllowedOriginPatterns(allowedOrigins);
+
+        config.setAllowedMethods(List.of("GET", "POST", "PUT", "DELETE", "OPTIONS"));
+        config.setAllowedHeaders(List.of("*"));
+        config.setAllowCredentials(true);
+
+        UrlBasedCorsConfigurationSource source = new UrlBasedCorsConfigurationSource();
+        source.registerCorsConfiguration("/**", config);
+
+        return source;
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/EmailConfigurationAdapter.java

@@ -1,12 +0,0 @@
-package com.pablotj.restemailbridge.infrastructure.config;
-
-import com.pablotj.restemailbridge.application.port.EmailConfigurationPort;
-import org.springframework.stereotype.Component;
-
-@Component
-public class EmailConfigurationAdapter implements EmailConfigurationPort {
-    @Override
-    public String getDefaultRecipient() {
-        return "1234@1234.com";
-    }
-}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/JpaConfig.java

@@ -0,0 +1,8 @@
+package com.pablotj.restemailbridge.infrastructure.config;
+
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
+
+@Configuration
+@EnableJpaAuditing
+public class JpaConfig { }

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/LocaleConfig.java

@@ -0,0 +1,25 @@
+package com.pablotj.restemailbridge.infrastructure.config;
+
+import java.util.List;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.web.servlet.LocaleResolver;
+import org.springframework.web.servlet.i18n.AcceptHeaderLocaleResolver;
+
+import java.util.Locale;
+
+@Configuration
+public class LocaleConfig {
+
+    @Bean
+    public LocaleResolver localeResolver() {
+        AcceptHeaderLocaleResolver resolver = new AcceptHeaderLocaleResolver();
+        resolver.setDefaultLocale(Locale.of("en"));
+        resolver.setSupportedLocales(
+                List.of(Locale.of("es"),
+                        Locale.of("en"),
+                        Locale.of("gl"))
+        );
+        return resolver;
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/MessageConfig.java

@@ -0,0 +1,27 @@
+package com.pablotj.restemailbridge.infrastructure.config;
+
+import org.springframework.context.MessageSource;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.ResourceBundleMessageSource;
+import org.springframework.validation.beanvalidation.LocalValidatorFactoryBean;
+
+@Configuration
+public class MessageConfig {
+
+    @Bean
+    public MessageSource messageSource() {
+        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
+        messageSource.setBasename("i18n/messages");
+        messageSource.setDefaultEncoding("UTF-8");
+        messageSource.setUseCodeAsDefaultMessage(false);
+        return messageSource;
+    }
+
+    @Bean
+    public LocalValidatorFactoryBean validator(MessageSource messageSource) {
+        LocalValidatorFactoryBean bean = new LocalValidatorFactoryBean();
+        bean.setValidationMessageSource(messageSource);
+        return bean;
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/OpenApiConfig.java

@@ -0,0 +1,46 @@
+package com.pablotj.restemailbridge.infrastructure.config;
+
+import io.swagger.v3.oas.models.OpenAPI;
+import io.swagger.v3.oas.models.info.Contact;
+import io.swagger.v3.oas.models.info.Info;
+import io.swagger.v3.oas.models.info.License;
+import io.swagger.v3.oas.models.parameters.Parameter;
+import io.swagger.v3.oas.models.media.StringSchema;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springdoc.core.customizers.OpenApiCustomizer;
+@Configuration
+public class OpenApiConfig {
+
+    @Bean
+    public OpenAPI customOpenAPI() {
+        return new OpenAPI()
+                .info(new Info()
+                        .title("Rest Email Bridge API")
+                        .version("v1")
+                        .description("API for sending and managing emails")
+                        .license(new License().name("Apache 2.0").url("https://www.apache.org/licenses/LICENSE-2.0"))
+                );
+    }
+
+
+    @Bean
+    public OpenApiCustomizer globalHeaderCustomizer() {
+        return openApi -> openApi.getPaths().values().forEach(pathItem ->
+                pathItem.readOperations().forEach(operation ->
+                        operation.addParametersItem(
+                                new Parameter()
+                                        .in("header")
+                                        .name("Accept-Language")
+                                        .description("Language for messages (en, es, gl)")
+                                        .required(false)
+                                        .schema(new StringSchema()
+                                                ._default("en")
+                                                .addEnumItem("en")
+                                                .addEnumItem("es")
+                                                .addEnumItem("gl"))
+                        )
+                )
+        );
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/SecurityConfig.java

@@ -0,0 +1,31 @@
+package com.pablotj.restemailbridge.infrastructure.config;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.security.config.annotation.web.builders.HttpSecurity;
+import org.springframework.security.config.annotation.web.configuration.EnableWebSecurity;
+import org.springframework.security.config.annotation.web.configurers.AbstractHttpConfigurer;
+import org.springframework.security.web.SecurityFilterChain;
+import org.springframework.web.cors.CorsConfigurationSource;
+
+@Configuration
+@EnableWebSecurity
+public class SecurityConfig {
+
+    private final CorsConfigurationSource corsConfigurationSource;
+
+    public SecurityConfig(CorsConfigurationSource corsConfigurationSource) {
+        this.corsConfigurationSource = corsConfigurationSource;
+    }
+
+    @Bean
+    public SecurityFilterChain securityFilterChain(HttpSecurity http) throws Exception {
+        http
+                .csrf(AbstractHttpConfigurer::disable)
+                .cors(cors -> cors.configurationSource(corsConfigurationSource))
+                .authorizeHttpRequests(auth -> auth
+                        .anyRequest().permitAll()
+                );
+        return http.build();
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/UseCaseConfig.java

@@ -0,0 +1,18 @@
+package com.pablotj.restemailbridge.infrastructure.config;
+
+import com.pablotj.restemailbridge.application.port.in.EmailDefaultConfigPort;
+import com.pablotj.restemailbridge.application.port.out.EmailPort;
+import com.pablotj.restemailbridge.application.usecase.SendEmailUseCase;
+import com.pablotj.restemailbridge.domain.repository.EmailRepository;
+import com.pablotj.restemailbridge.domain.service.EmailValidatorService;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class UseCaseConfig {
+
+    @Bean
+    public SendEmailUseCase sendEmailUseCase(EmailDefaultConfigPort emailConfigurationPort, EmailPort emailService, EmailRepository emailRepository) {
+        return new SendEmailUseCase(new EmailValidatorService(), emailConfigurationPort, emailService, emailRepository);
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/config/spring/UseCaseConfig.java

@@ -1,17 +0,0 @@
-package com.pablotj.restemailbridge.infrastructure.config.spring;
-
-import com.pablotj.restemailbridge.application.port.EmailConfigurationPort;
-import com.pablotj.restemailbridge.application.usecase.SendEmailUseCase;
-import com.pablotj.restemailbridge.domain.repository.EmailRepository;
-import com.pablotj.restemailbridge.domain.service.EmailService;
-import org.springframework.context.annotation.Bean;
-import org.springframework.context.annotation.Configuration;
-
-@Configuration
-public class UseCaseConfig {
-
-    @Bean
-    public SendEmailUseCase sendEmailUseCase(EmailConfigurationPort emailConfigurationPort, EmailService emailService, EmailRepository emailRepository) {
-        return new SendEmailUseCase(emailConfigurationPort, emailService, emailRepository);
-    }
-}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/encryption/EncryptionConverter.java

@@ -0,0 +1,23 @@
+package com.pablotj.restemailbridge.infrastructure.encryption;
+
+import jakarta.persistence.AttributeConverter;
+import jakarta.persistence.Converter;
+import org.springframework.beans.factory.annotation.Value;
+
+@Converter
+public class EncryptionConverter implements AttributeConverter<String, String> {
+
+
+    @Value("${app.encryption.secret}")
+    private String secret;
+
+    @Override
+    public String convertToDatabaseColumn(String attribute) {
+        return attribute == null ? null : new EncryptionUtils(secret).encrypt(attribute);
+    }
+
+    @Override
+    public String convertToEntityAttribute(String dbData) {
+        return dbData == null ? null : new EncryptionUtils(secret).decrypt(dbData);
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/encryption/EncryptionUtils.java

@@ -0,0 +1,72 @@
+package com.pablotj.restemailbridge.infrastructure.encryption;
+
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.security.SecureRandom;
+import java.util.Base64;
+import javax.crypto.Cipher;
+import javax.crypto.SecretKey;
+import javax.crypto.spec.GCMParameterSpec;
+import javax.crypto.spec.SecretKeySpec;
+
+public class EncryptionUtils {
+
+    private static final String ALGORITHM = "AES";
+    private static final String TRANSFORMATION = "AES/GCM/NoPadding";
+    private static final int TAG_LENGTH_BIT = 128;
+    private static final int IV_LENGTH_BYTE = 12;
+    private static final SecureRandom secureRandom = new SecureRandom();
+
+    private final SecretKey secretKey;
+
+    public EncryptionUtils(String secret) {
+        if (secret == null || secret.getBytes(StandardCharsets.UTF_8).length != 32) {
+            throw new IllegalArgumentException("Secret key must be 32 bytes for AES-256");
+        }
+        this.secretKey = new SecretKeySpec(secret.getBytes(StandardCharsets.UTF_8), ALGORITHM);
+    }
+
+    public String encrypt(String plainText) {
+        try {
+            byte[] iv = new byte[IV_LENGTH_BYTE];
+            secureRandom.nextBytes(iv);
+
+            Cipher cipher = Cipher.getInstance(TRANSFORMATION);
+            GCMParameterSpec spec = new GCMParameterSpec(TAG_LENGTH_BIT, iv);
+            cipher.init(Cipher.ENCRYPT_MODE, secretKey, spec);
+
+            byte[] cipherText = cipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8));
+
+            // Guardamos IV + ciphertext juntos
+            ByteBuffer byteBuffer = ByteBuffer.allocate(iv.length + cipherText.length);
+            byteBuffer.put(iv);
+            byteBuffer.put(cipherText);
+
+            return Base64.getEncoder().encodeToString(byteBuffer.array());
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to encrypt text", e);
+        }
+    }
+
+    public String decrypt(String base64CipherText) {
+        try {
+            byte[] cipherMessage = Base64.getDecoder().decode(base64CipherText);
+            ByteBuffer byteBuffer = ByteBuffer.wrap(cipherMessage);
+
+            byte[] iv = new byte[IV_LENGTH_BYTE];
+            byteBuffer.get(iv);
+
+            byte[] cipherText = new byte[byteBuffer.remaining()];
+            byteBuffer.get(cipherText);
+
+            Cipher cipher = Cipher.getInstance(TRANSFORMATION);
+            GCMParameterSpec spec = new GCMParameterSpec(TAG_LENGTH_BIT, iv);
+            cipher.init(Cipher.DECRYPT_MODE, secretKey, spec);
+
+            byte[] plainText = cipher.doFinal(cipherText);
+            return new String(plainText, StandardCharsets.UTF_8);
+        } catch (Exception e) {
+            throw new RuntimeException("Failed to decrypt text", e);
+        }
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/exception/GmailConfigurationException.java

@@ -0,0 +1,13 @@
+package com.pablotj.restemailbridge.infrastructure.exception;
+
+import java.io.Serial;
+
+public class GmailConfigurationException extends RuntimeException {
+
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    public GmailConfigurationException(String message) {
+        super(message);
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/exception/GmailInitializationException.java

@@ -0,0 +1,13 @@
+package com.pablotj.restemailbridge.infrastructure.exception;
+
+import java.io.Serial;
+
+public class GmailInitializationException extends RuntimeException {
+
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    public GmailInitializationException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/exception/GmailSendErrorException.java

@@ -0,0 +1,14 @@
+package com.pablotj.restemailbridge.infrastructure.exception;
+
+import java.io.Serial;
+
+public class GmailSendErrorException extends RuntimeException {
+
+    @Serial
+    private static final long serialVersionUID = 1L;
+
+    public GmailSendErrorException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/mail/GmailDefaultConfigAdapter.java

@@ -0,0 +1,12 @@
+package com.pablotj.restemailbridge.infrastructure.mail;
+
+import com.pablotj.restemailbridge.application.port.in.EmailDefaultConfigPort;
+import org.springframework.stereotype.Component;
+
+@Component
+public class GmailDefaultConfigAdapter implements EmailDefaultConfigPort {
+    @Override
+    public String getDefaultRecipient() {
+        return "pablodelatorree@gmail.com";
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/mail/GmailOAuth2MailAdapter.java

@@ -0,0 +1,182 @@
+package com.pablotj.restemailbridge.infrastructure.mail;
+
+import com.google.api.client.auth.oauth2.Credential;
+import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
+import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
+import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
+import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
+import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
+import com.google.api.client.json.JsonFactory;
+import com.google.api.client.json.gson.GsonFactory;
+import com.google.api.client.util.store.FileDataStoreFactory;
+import com.google.api.services.gmail.Gmail;
+import com.google.api.services.gmail.GmailScopes;
+import com.google.api.services.gmail.model.Message;
+import com.pablotj.restemailbridge.domain.model.Email;
+import com.pablotj.restemailbridge.application.port.out.EmailPort;
+import com.pablotj.restemailbridge.infrastructure.exception.GmailConfigurationException;
+import com.pablotj.restemailbridge.infrastructure.exception.GmailInitializationException;
+import com.pablotj.restemailbridge.infrastructure.exception.GmailSendErrorException;
+import com.pablotj.restemailbridge.infrastructure.mail.config.GmailOAuth2Properties;
+import jakarta.annotation.PostConstruct;
+import jakarta.mail.MessagingException;
+import jakarta.mail.Session;
+import jakarta.mail.internet.InternetAddress;
+import jakarta.mail.internet.MimeMessage;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.stereotype.Component;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.util.Base64;
+import java.util.Collections;
+import java.util.List;
+import java.util.Properties;
+
+/**
+ * Gmail implementation of the EmailPort using OAuth2 authentication.
+ * <p>
+ * Handles sending emails via Gmail API and manages credentials stored in a local token folder.
+ */
+@Component
+public class GmailOAuth2MailAdapter implements EmailPort {
+
+    private static final Logger log = LoggerFactory.getLogger(GmailOAuth2MailAdapter.class);
+    private static final String APPLICATION_NAME = "MailServiceApi";
+    private static final JsonFactory JSON_FACTORY = GsonFactory.getDefaultInstance();
+    private static final List<String> SCOPES = Collections.singletonList(GmailScopes.GMAIL_SEND);
+    private static final String TOKENS_DIRECTORY_PATH = "/app/tokens";
+
+    private final GmailOAuth2Properties properties;
+    private Gmail service;
+
+    /**
+     * Constructor injecting Gmail OAuth2 properties.
+     *
+     * @param properties OAuth2 configuration for Gmail
+     */
+    public GmailOAuth2MailAdapter(GmailOAuth2Properties properties) {
+        this.properties = properties;
+    }
+
+    /**
+     * Initializes the Gmail client with OAuth2 credentials.
+     * <p>
+     * Loads the token from the token folder, sets up the OAuth2 flow,
+     * and initializes the Gmail API client.
+     *
+     * @throws GmailConfigurationException if token folder or credentials are missing
+     * @throws GmailInitializationException if any other initialization error occurs
+     */
+    @PostConstruct
+    public void init() {
+        try {
+            log.info("Initializing Gmail OAuth2 client...");
+
+            GoogleClientSecrets clientSecrets = new GoogleClientSecrets()
+                    .setInstalled(
+                            new GoogleClientSecrets.Details()
+                                    .setClientId(properties.clientId())
+                                    .setClientSecret(properties.clientSecret())
+                                    .setRedirectUris(Collections.singletonList(properties.redirectUri()))
+                    );
+
+            File tokenFolder = new File(TOKENS_DIRECTORY_PATH);
+            if (!tokenFolder.exists() || !tokenFolder.isDirectory()) {
+                log.error("Token folder not found: {}", TOKENS_DIRECTORY_PATH);
+                throw new GmailConfigurationException("Token folder missing: " + TOKENS_DIRECTORY_PATH);
+            }
+
+            GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
+                    GoogleNetHttpTransport.newTrustedTransport(),
+                    JSON_FACTORY,
+                    clientSecrets,
+                    SCOPES)
+                    .setDataStoreFactory(new FileDataStoreFactory(tokenFolder))
+                    .setAccessType("offline")
+                    .build();
+
+            LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(8888).build();
+            Credential credential = new AuthorizationCodeInstalledApp(flow, receiver).authorize("user");
+            if (credential == null) {
+                log.error("No stored credentials found. Generate tokens first.");
+                throw new GmailConfigurationException("No stored credentials found. Generate tokens first.");
+            }
+
+            service = new Gmail.Builder(GoogleNetHttpTransport.newTrustedTransport(), JSON_FACTORY, credential)
+                    .setApplicationName(APPLICATION_NAME)
+                    .build();
+
+            log.info("Gmail OAuth2 client initialized successfully.");
+
+        } catch (Exception e) {
+            if (e instanceof GmailConfigurationException configEx) {
+                throw configEx;
+            }
+            log.error("Failed to initialize Gmail client");
+            throw new GmailInitializationException("Failed to initialize Gmail client", e);
+        }
+    }
+
+    /**
+     * Sends an email using the Gmail API.
+     *
+     * @param email Email object containing recipient, sender, subject, and body
+     * @return The same Email object after sending
+     * @throws GmailSendErrorException if sending fails
+     */
+    @Override
+    public Email sendEmail(Email email) {
+        try {
+            log.info("Sending email to {}", email.getTo());
+            MimeMessage message = createEmail(email.getTo(), email.getFrom(), email.getSubject(), email.getBody());
+            sendMessage(service, message);
+            log.info("Email sent successfully to {}", email.getTo());
+        } catch (Exception e) {
+            log.error("Failed to send email to {}", email.getTo());
+            throw new GmailSendErrorException("Failed to send email", e);
+        }
+        return email;
+    }
+
+    /**
+     * Creates a MimeMessage from the given parameters.
+     *
+     * @param to       Recipient email
+     * @param from     Sender email
+     * @param subject  Email subject
+     * @param bodyText Email body
+     * @return MimeMessage ready to be sent
+     * @throws MessagingException if creation fails
+     */
+    private static MimeMessage createEmail(String to, String from, String subject, String bodyText) throws MessagingException {
+        Properties props = new Properties();
+        Session session = Session.getDefaultInstance(props, null);
+        MimeMessage email = new MimeMessage(session);
+        email.setReplyTo(new jakarta.mail.Address[]{new InternetAddress(from)});
+        email.setFrom(new InternetAddress(from));
+        email.addRecipient(jakarta.mail.Message.RecipientType.TO, new InternetAddress(to));
+        email.setSubject(subject);
+        email.setText(bodyText);
+        return email;
+    }
+
+    /**
+     * Sends the MimeMessage using the Gmail API.
+     *
+     * @param service Gmail client
+     * @param email   MimeMessage to send
+     * @throws MessagingException if message creation fails
+     * @throws IOException        if API call fails
+     */
+    private static void sendMessage(Gmail service, MimeMessage email) throws MessagingException, IOException {
+        ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+        email.writeTo(buffer);
+        String encodedEmail = Base64.getUrlEncoder().encodeToString(buffer.toByteArray());
+        Message message = new Message();
+        message.setRaw(encodedEmail);
+        service.users().messages().send("me", message).execute();
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/mail/GmailOAuth2MailService.java

@@ -1,15 +0,0 @@
-package com.pablotj.restemailbridge.infrastructure.mail;
-
-import com.pablotj.restemailbridge.domain.model.Email;
-import com.pablotj.restemailbridge.domain.service.EmailService;
-import org.springframework.stereotype.Component;
-
-@Component
-public class GmailOAuth2MailService implements EmailService {
-
-    @Override
-    public Email sendEmail(Email email) {
-        System.out.println("Sending email " + email.getSubject() + " to " + email.getTo());
-        return email;
-    }
-}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/mail/config/GmailConfig.java

@@ -0,0 +1,9 @@
+package com.pablotj.restemailbridge.infrastructure.mail.config;
+
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+@EnableConfigurationProperties(GmailOAuth2Properties.class)
+public class GmailConfig {
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/mail/config/GmailOAuth2Properties.java

@@ -0,0 +1,10 @@
+package com.pablotj.restemailbridge.infrastructure.mail.config;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+@ConfigurationProperties(prefix = "gmail.oauth2")
+public record GmailOAuth2Properties(
+        String clientId,
+        String clientSecret,
+        String redirectUri
+) {}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/persistence/MailJpa.java

@@ -1,15 +1,25 @@
 package com.pablotj.restemailbridge.infrastructure.persistence;
 
+import com.pablotj.restemailbridge.domain.model.EmailStatus;
+import com.pablotj.restemailbridge.infrastructure.encryption.EncryptionConverter;
 import jakarta.persistence.Column;
+import jakarta.persistence.Convert;
 import jakarta.persistence.Entity;
+import jakarta.persistence.EntityListeners;
+import jakarta.persistence.EnumType;
+import jakarta.persistence.Enumerated;
 import jakarta.persistence.GeneratedValue;
 import jakarta.persistence.GenerationType;
 import jakarta.persistence.Id;
 import jakarta.persistence.Table;
+import java.time.Instant;
 import lombok.Getter;
 import lombok.Setter;
+import org.springframework.data.annotation.CreatedDate;
+import org.springframework.data.jpa.domain.support.AuditingEntityListener;
 
 @Entity
+@EntityListeners(AuditingEntityListener.class)
 @Table(name = "MAIL")
 @Getter
 @Setter
@@ -19,15 +29,29 @@ public class MailJpa {
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
 
-    @Column(nullable = false)
+    @Column(length = 200, nullable = false)
+    @Convert(converter = EncryptionConverter.class)
     private String sender;
 
-    @Column(nullable = false)
+    @Column(length = 200, nullable = false)
     private String recipient;
 
-    @Column(nullable = false)
+    @Column(length = 150, nullable = false)
+    @Convert(converter = EncryptionConverter.class)
     private String subjet;
 
-    @Column(nullable = false)
+    @Column(length = 7000, nullable = false)
+    @Convert(converter = EncryptionConverter.class)
     private String body;
+
+    @Column(nullable = false)
+    @Enumerated(EnumType.STRING)
+    private EmailStatus status;
+
+    @CreatedDate
+    @Column(nullable = false)
+    private Instant createdAt;
+
+    @Column
+    private String errorDescription;
 }

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/persistence/MailRepositoryAdapter.java

@@ -20,7 +20,8 @@ public class MailRepositoryAdapter implements EmailRepository {
         mailJpa.setRecipient(email.getTo());
         mailJpa.setSubjet(email.getSubject());
         mailJpa.setBody(email.getBody());
-
+        mailJpa.setStatus(email.getStatus());
+        mailJpa.setErrorDescription(email.getErrorDescription());
         springDataMailRepository.save(mailJpa);
 
         return email;

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/rest/GlobalExceptionHandler.java

@@ -0,0 +1,26 @@
+package com.pablotj.restemailbridge.infrastructure.rest;
+
+import java.util.HashMap;
+import java.util.Map;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+import org.springframework.web.bind.annotation.RestControllerAdvice;
+
+@RestControllerAdvice
+public class GlobalExceptionHandler {
+
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    public ResponseEntity<Map<String, String>> handleValidationExceptions(MethodArgumentNotValidException ex) {
+        Map<String, String> errors = new HashMap<>();
+        ex.getBindingResult().getFieldErrors().forEach(error ->
+                errors.put(error.getField(), error.getDefaultMessage()));
+        return ResponseEntity.badRequest().body(errors);
+    }
+
+    @ExceptionHandler(RuntimeException.class)
+    public ResponseEntity<Map<String, String>> handleRuntimeException(RuntimeException ex) {
+        Map<String, String> error = Map.of("error", ex.getMessage());
+        return ResponseEntity.unprocessableEntity().body(error); // 422
+    }
+}

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/rest/MailController.java

@@ -3,6 +3,13 @@ package com.pablotj.restemailbridge.infrastructure.rest;
 import com.pablotj.restemailbridge.application.dto.EmailDTO;
 import com.pablotj.restemailbridge.application.usecase.SendEmailUseCase;
 import com.pablotj.restemailbridge.infrastructure.rest.dto.SendMailRequest;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.media.Content;
+import io.swagger.v3.oas.annotations.media.ExampleObject;
+import io.swagger.v3.oas.annotations.media.Schema;
+import io.swagger.v3.oas.annotations.responses.ApiResponse;
+import io.swagger.v3.oas.annotations.responses.ApiResponses;
+import io.swagger.v3.oas.annotations.tags.Tag;
 import jakarta.validation.Valid;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -10,18 +17,76 @@ import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.RestController;
 
+/**
+ * REST controller responsible for handling email-related requests.
+ * <p>
+ * Exposes endpoints under {@code /v1/mail} to send emails through the system.
+ * Delegates business logic to the {@link SendEmailUseCase}.
+ */
 @RestController
 @RequestMapping("/v1/mail")
+@Tag(name = "Mail API", description = "Endpoints for sending emails")
 public class MailController {
 
     private final SendEmailUseCase sendEmailUseCase;
 
+    /**
+     * Creates a new {@link MailController} instance.
+     *
+     * @param sendEmailUseCase the use case responsible for sending emails
+     */
     public MailController(SendEmailUseCase sendEmailUseCase) {
         this.sendEmailUseCase = sendEmailUseCase;
     }
 
-
+    /**
+     * Sends a new email using the provided request data.
+     * <p>
+     * The request payload is validated using {@link jakarta.validation.Valid}.
+     *
+     * @param request the email request containing sender, subject and body
+     * @return {@link ResponseEntity} with HTTP 200 (OK) if the email is sent successfully
+     */
     @PostMapping
+    @Operation(
+            summary = "Send an email",
+            description = "Sends an email using the provided sender, subject, and body.",
+            requestBody = @io.swagger.v3.oas.annotations.parameters.RequestBody(
+                    required = true,
+                    content =  @Content(
+                            mediaType = "application/json",
+                            examples = @ExampleObject(
+                                    name = "Basic email",
+                                    value = "{ \"from\": \"user@example.com\", \"subject\": \"Hello\", \"body\": \"Hi there!\" }"
+                            )
+                    )
+            )
+    )
+    @ApiResponses(value = {
+            @ApiResponse(responseCode = "200", description = "Email sent successfully"),
+            @ApiResponse(responseCode = "400", description = "Invalid request payload"),
+            @ApiResponse(
+                    responseCode = "401",
+                    description = "Unauthorized – missing or invalid authentication token",
+                    content = @Content(schema = @Schema(hidden = true))
+            ),
+            @ApiResponse(
+                    responseCode = "403",
+                    description = "Forbidden – the authenticated user cannot send to the specified recipient",
+                    content = @Content(schema = @Schema(hidden = true))
+            ),
+            @ApiResponse(
+                    responseCode = "422",
+                    description = "Unprocessable Entity – domain validation failed (e.g. invalid email address, business rule violation)",
+                    content = @Content(
+                            mediaType = "application/json",
+                            schema = @Schema(
+                                    example = "{ \"error\": \"Invalid recipient domain\" }"
+                            )
+                    )
+            ),
+            @ApiResponse(responseCode = "500", description = "Unexpected server error")
+    })
     public ResponseEntity<Void> send(@Valid @RequestBody SendMailRequest request) {
         sendEmailUseCase.handle(new EmailDTO(request.from(), request.subject(), request.body()));
         return ResponseEntity.ok().build();

infrastructure/src/main/java/com/pablotj/restemailbridge/infrastructure/rest/dto/SendMailRequest.java

@@ -1,8 +1,26 @@
 package com.pablotj.restemailbridge.infrastructure.rest.dto;
 
+import io.swagger.v3.oas.annotations.media.Schema;
+import jakarta.validation.constraints.Email;
+import jakarta.validation.constraints.NotBlank;
+import org.hibernate.validator.constraints.Length;
+
+@Schema(description = "Request payload to send an email")
 public record SendMailRequest(
+        @NotBlank(message = "{email.from.blank}")
+        @Email(message = "{email.from.invalid}")
+        @Length(min = 4, max = 100, message = "email.from.length}")
+        @Schema(description = "Sender email address", example = "user@example.com")
         String from,
+
+        @NotBlank(message = "{email.subject.blank}")
+        @Length(min=1, max = 30, message = "{email.subject.length}")
+        @Schema(description = "Email subject", example = "Welcome to RestEmailBridge")
         String subject,
+
+        @NotBlank(message = "{email.body.blank}")
+        @Length(min=1, max = 4000, message = "{email.body.length}")
+        @Schema(description = "Email body content", example = "Hello, thanks for signing up!")
         String body
 ) {
 }

infrastructure/src/main/resources/db-scripts/V1.0.0_DDL_init_scheme.sql

@@ -1,8 +1,18 @@
-CREATE TABLE restemailbridge.mail
+create table mail
 (
-    id       BIGSERIAL PRIMARY KEY,
-    body     VARCHAR(255) NOT NULL,
-    recipient VARCHAR(255) NOT NULL,
-    sender   VARCHAR(255) NOT NULL,
-    subject  VARCHAR(255) NOT NULL
+    id                bigint generated by default as identity primary key,
+    body              varchar(7000) not null,
+    recipient         varchar(200) not null,
+    sender            varchar(200) not null,
+    subjet            varchar(150) not null,
+    created_at        timestamp,
+    status            varchar
+        constraint check_status
+            check (((status)::text = 'PENDING'::text) OR ((status)::text = 'SENT'::text) OR
+                   ((status)::text = 'FAILED'::text)),
+    error_description varchar(10000),
+    constraint check_error_description
+        check ((((status)::text = 'FAILED'::text) AND
+                ((error_description IS NOT NULL) OR ((error_description)::text <> ''::text))) OR
+               (((status)::text <> 'FAILED'::text) AND (error_description IS NULL)))
 );

infrastructure/src/main/resources/i18n/messages.properties

@@ -0,0 +1,9 @@
+email.from.invalid=Sender email must be valid
+email.from.blank=Sender email cannot be blank
+email.from.length=Sender email must be between 4 and 100 characters
+
+email.subject.blank=Subject cannot be blank
+email.subject.length=Subject must be between 1 and 30 characters
+
+email.body.blank=Body cannot be blank
+email.body.length=Body must be between 1 and 4000 characters

infrastructure/src/main/resources/i18n/messages_es.properties

@@ -0,0 +1,9 @@
+email.from.invalid=El remitente debe ser un correo válido
+email.from.blank=El remitente no puede estar vacío
+email.from.length=El remitente debe tener entre 4 y 100 caracteres
+
+email.subject.blank=El asunto no puede estar vacío
+email.subject.length=El asunto debe tener entre 1 y 30 caracteres
+
+email.body.blank=El cuerpo no puede estar vacío
+email.body.length=El cuerpo debe tener entre 1 y 4000 caracteres

infrastructure/src/main/resources/i18n/messages_gl.properties

@@ -0,0 +1,9 @@
+email.from.invalid=O remitente debe ser un correo válido
+email.from.blank=O remitente non pode estar baleiro
+email.from.length=O remitente debe ter entre 4 e 100 caracteres
+
+email.subject.blank=O asunto non pode estar baleiro
+email.subject.length=O asunto debe ter entre 1 e 30 caracteres
+
+email.body.blank=O corpo non pode estar baleiro
+email.body.length=O corpo debe ter entre 1 e 4000 caracteres

infrastructure/src/main/resources/log4j2.properties

@@ -0,0 +1,99 @@
+# ========== Log4j2 Properties Configuration ==========
+status = error
+name = PropertiesConfig
+
+property.basePath = logs
+
+# ========== Appenders ==========
+
+# Console
+appender.console.type = Console
+appender.console.name = ConsoleAppender
+appender.console.layout.type = PatternLayout
+appender.console.layout.pattern = [%d{yyyy-MM-dd HH:mm:ss}] [%t] %-5level %logger{36} - %msg%n
+
+# Rolling File INFO+ (DEBUG e INFO)
+appender.info.type = RollingFile
+appender.info.name = InfoFileAppender
+appender.info.fileName = ${basePath}/info.log
+appender.info.filePattern = ${basePath}/info-%d{yyyy-MM-dd}-%i.log.gz
+appender.info.layout.type = PatternLayout
+appender.info.layout.pattern = [%d{yyyy-MM-dd HH:mm:ss}] [%t] %-5level %logger{36} - %msg%n
+appender.info.policies.type = Policies
+appender.info.policies.time.type = TimeBasedTriggeringPolicy
+appender.info.policies.time.interval = 1
+appender.info.policies.size.type = SizeBasedTriggeringPolicy
+appender.info.policies.size.size = 10MB
+appender.info.filter.threshold.type = ThresholdFilter
+appender.info.filter.threshold.level = debug
+appender.info.filter.threshold.onMatch = ACCEPT
+appender.info.filter.threshold.onMismatch = DENY
+
+# Rolling File ERROR+ (ERROR y FATAL)
+appender.error.type = RollingFile
+appender.error.name = ErrorFileAppender
+appender.error.fileName = ${basePath}/error.log
+appender.error.filePattern = ${basePath}/error-%d{yyyy-MM-dd}-%i.log.gz
+appender.error.layout.type = PatternLayout
+appender.error.layout.pattern = [%d{yyyy-MM-dd HH:mm:ss}] [%t] %-5level %logger{36} - %msg%n
+appender.error.policies.type = Policies
+appender.error.policies.time.type = TimeBasedTriggeringPolicy
+appender.error.policies.time.interval = 1
+appender.error.policies.size.type = SizeBasedTriggeringPolicy
+appender.error.policies.size.size = 10MB
+appender.error.filter.threshold.type = ThresholdFilter
+appender.error.filter.threshold.level = error
+appender.error.filter.threshold.onMatch = ACCEPT
+appender.error.filter.threshold.onMismatch = DENY
+
+# Rolling File for Database logs (Hibernate / JDBC)
+appender.db.type = RollingFile
+appender.db.name = DBFileAppender
+appender.db.fileName = ${basePath}/db.log
+appender.db.filePattern = ${basePath}/db-%d{yyyy-MM-dd}-%i.log.gz
+appender.db.layout.type = PatternLayout
+appender.db.layout.pattern = [%d{yyyy-MM-dd HH:mm:ss}] [%t] %-5level %logger{36} - %msg%n
+appender.db.policies.type = Policies
+appender.db.policies.time.type = TimeBasedTriggeringPolicy
+appender.db.policies.time.interval = 1
+appender.db.policies.size.type = SizeBasedTriggeringPolicy
+appender.db.policies.size.size = 10MB
+
+# ========== Loggers ==========
+
+# App logs
+logger.app.name = com.pablotj
+logger.app.level = debug
+logger.app.additivity = false
+logger.app.appenderRefs = console, info, error
+logger.app.appenderRef.console.ref = ConsoleAppender
+logger.app.appenderRef.info.ref = InfoFileAppender
+logger.app.appenderRef.error.ref = ErrorFileAppender
+
+# Hibernate SQL
+logger.hibernate.name = org.hibernate.SQL
+logger.hibernate.level = debug
+logger.hibernate.additivity = false
+logger.hibernate.appenderRefs = db
+logger.hibernate.appenderRef.db.ref = DBFileAppender
+
+# Hibernate parameter binding
+#logger.hibernate.type.name = org.hibernate.type.descriptor.sql.BasicBinder
+#logger.hibernate.type.level = trace
+#logger.hibernate.type.additivity = false
+#logger.hibernate.type.appenderRefs = db
+#logger.hibernate.type.appenderRef.db.ref = DBFileAppender
+
+# Spring JDBC Template logs
+#logger.spring.sql.name = org.springframework.jdbc.core.JdbcTemplate
+#logger.spring.sql.level = debug
+#logger.spring.sql.additivity = false
+#logger.spring.sql.appenderRefs = db
+#logger.spring.sql.appenderRef.db.ref = DBFileAppender
+
+# ========== Root Logger ==========
+rootLogger.level = info
+rootLogger.appenderRefs = console, info, error
+rootLogger.appenderRef.console.ref = ConsoleAppender
+rootLogger.appenderRef.info.ref = InfoFileAppender
+rootLogger.appenderRef.error.ref = ErrorFileAppender

infrastructure/src/test/java/com/pablotj/restemailbridge/infrastructure/RestEmailBridgeTestApplication.java

@@ -0,0 +1,11 @@
+package com.pablotj.restemailbridge.infrastructure;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.boot.autoconfigure.domain.EntityScan;
+import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
+
+@SpringBootApplication(scanBasePackages = "com.pablotj.restemailbridge")
+@EnableJpaRepositories(basePackages = "com.pablotj.restemailbridge")
+@EntityScan(basePackages = "com.pablotj.restemailbridge")
+public class RestEmailBridgeTestApplication {
+}

infrastructure/src/test/java/com/pablotj/restemailbridge/infrastructure/persistence/MailRepositoryAdapterIT.java

@@ -0,0 +1,40 @@
+package com.pablotj.restemailbridge.infrastructure.persistence;
+
+import com.pablotj.restemailbridge.domain.model.Email;
+import com.pablotj.restemailbridge.domain.model.EmailStatus;
+import com.pablotj.restemailbridge.infrastructure.config.JpaConfig;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+import org.springframework.context.annotation.Import;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@Import(JpaConfig.class)
+@DataJpaTest
+class MailRepositoryAdapterIT {
+
+    @Autowired
+    private SpringDataMailRepository springDataMailRepository;
+
+    @Test
+    void shouldSaveEmailSuccessfully() {
+        MailRepositoryAdapter adapter = new MailRepositoryAdapter(springDataMailRepository);
+
+        Email email = Email.create("sender@example.com", "recipient@example.com", "Subject", "Body");
+
+        Email saved = adapter.save(email);
+
+        assertThat(saved.getFrom()).isEqualTo("sender@example.com");
+        assertThat(saved.getTo()).isEqualTo("recipient@example.com");
+        assertThat(saved.getSubject()).isEqualTo("Subject");
+        assertThat(saved.getBody()).isEqualTo("Body");
+        assertThat(saved.getStatus()).isEqualTo(EmailStatus.PENDING);
+
+        assertThat(springDataMailRepository.findAll())
+                .hasSize(1)
+                .first()
+                .extracting("sender", "recipient")
+                .containsExactly("sender@example.com", "recipient@example.com");
+    }
+}

infrastructure/src/test/java/com/pablotj/restemailbridge/infrastructure/rest/MailControllerIT.java

@@ -0,0 +1,53 @@
+package com.pablotj.restemailbridge.infrastructure.rest;
+
+import com.pablotj.restemailbridge.application.port.out.EmailPort;
+import com.pablotj.restemailbridge.infrastructure.RestEmailBridgeTestApplication;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.http.MediaType;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.test.web.servlet.MockMvc;
+
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+@SpringBootTest(
+        classes = RestEmailBridgeTestApplication.class,
+        webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT
+)
+@AutoConfigureMockMvc
+@ActiveProfiles("test")
+class MailControllerIT {
+
+    @Autowired
+    private MockMvc mockMvc;
+
+    @MockBean
+    private EmailPort emailPort;
+
+    @Test
+    void shouldReturn200WhenEmailIsSent() throws Exception {
+        when(emailPort.sendEmail(any())).thenAnswer(invocation -> invocation.getArgument(0));
+
+        mockMvc.perform(post("/v1/mail")
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content("{\"from\":\"sender@example.com\",\"subject\":\"Subject\",\"body\":\"Body\"}"))
+                .andExpect(status().isOk());
+
+        verify(emailPort).sendEmail(any());
+    }
+
+    @Test
+    void shouldReturn400WhenRequestIsInvalid() throws Exception {
+        mockMvc.perform(post("/v1/mail")
+                        .contentType(MediaType.APPLICATION_JSON)
+                        .content("{\"subject\":\"Subject\",\"body\":\"Body\"}"))
+                .andExpect(status().isBadRequest());
+    }
+}

infrastructure/src/test/resources/application.yml

@@ -0,0 +1,27 @@
+spring:
+  application:
+    name: restemailbridge
+  datasource:
+    url: jdbc:h2:mem:restemailbridge;DB_CLOSE_DELAY=-1;DB_CLOSE_ON_EXIT=FALSE
+    driver-class-name: org.h2.Driver
+    username: sa
+    password:
+  jpa:
+    hibernate:
+      ddl-auto: create-drop
+    show-sql: true
+
+server:
+  port: 0
+  servlet:
+    context-path: /api
+
+app:
+  encryption:
+    secret: 0123456789ABCDEF0123456789ABCDEF
+
+gmail:
+  oauth2:
+    clientId: dummy
+    clientSecret: dummy
+    redirectUri: http://localhost:8888/Callback