Create an Application to Send Email Using Jakarta Mail

package com.example;

import io.micronaut.email.Email;
import io.micronaut.email.EmailException;
import io.micronaut.email.EmailSender;
import io.micronaut.http.HttpResponse;
import io.micronaut.http.annotation.Body;
import io.micronaut.http.annotation.Controller;
import io.micronaut.http.annotation.Post;
import io.micronaut.scheduling.TaskExecutors;
import io.micronaut.scheduling.annotation.ExecuteOn;

import static io.micronaut.email.BodyType.HTML;

@ExecuteOn(TaskExecutors.IO) (1)
@Controller("/email") (2)
public class EmailController {

    private final EmailSender<?, ?> emailSender;

    EmailController(EmailSender<?, ?> emailSender) { (3)
        this.emailSender = emailSender;
    }

    @Post("/send") (4)
    public HttpResponse<?> send(@Body("to") String to) { (5)

        try {
            emailSender.send(Email.builder()
                    .to(to)
                    .subject("Sending email with JavaMail is Fun")
                    .body("and <em>easy</em> to do anywhere with <strong>Micronaut Email</strong>", HTML)); (6)
        } catch (EmailException ignored) {
            return HttpResponse.unprocessableEntity(); (7)
        }

        return HttpResponse.accepted(); (8)
    }
}

javamail.authentication.password=${FROM_PASSWORD}
javamail.authentication.username=${FROM_EMAIL}
javamail.properties.mail.smtp.auth=true
javamail.properties.mail.smtp.host=smtp.gmail.com
javamail.properties.mail.smtp.port=465
javamail.properties.mail.smtp.ssl.enable=true
javamail.properties.mail.smtp.starttls.enable=false
micronaut.application.name=email-demo
micronaut.email.from.email=${FROM_EMAIL}
micronaut.email.from.name=${FROM_NAME\:}

package com.example;

import io.micronaut.context.annotation.Property;
import io.micronaut.email.Email;
import io.micronaut.email.EmailException;
import io.micronaut.email.TransactionalEmailSender;
import io.micronaut.http.HttpRequest;
import io.micronaut.http.client.HttpClient;
import io.micronaut.http.client.annotation.Client;
import io.micronaut.test.annotation.MockBean;
import io.micronaut.test.extensions.junit5.annotation.MicronautTest;
import jakarta.inject.Inject;
import jakarta.inject.Named;
import org.junit.jupiter.api.Test;

import jakarta.mail.Message;
import java.util.Map;
import java.util.function.Consumer;

import static io.micronaut.email.BodyType.HTML;
import static io.micronaut.http.HttpStatus.ACCEPTED;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertNotNull;

@Property(name = "FROM_EMAIL", value = "bob@gdk.example") (1)
@Property(name = "FROM_PASSWORD", value = "example-password")
@MicronautTest (2)
public class EmailControllerTest {

    @Inject
    @Client("/")
    HttpClient client; (3)

    Email sentEmail;

    @Test
    void testSend() {
        var response = client.toBlocking().exchange(
                HttpRequest.POST("/email/send",
                        Map.of("to", "alice@gdk.example"))); (4)

        assertEquals(ACCEPTED, response.status());

        assertNotNull(sentEmail);
        assertEquals("bob@gdk.example", sentEmail.getFrom().getEmail());
        assertEquals(1, sentEmail.getTo().size());
        assertEquals("alice@gdk.example", sentEmail.getTo().stream().findFirst().get().getEmail());
        assertEquals("Sending email with JavaMail is Fun", sentEmail.getSubject());
        assertNotNull(sentEmail.getBody());
        assertEquals("and <em>easy</em> to do anywhere with <strong>Micronaut Email</strong>",
                sentEmail.getBody().get(HTML).get());

    }

    @MockBean(TransactionalEmailSender.class) (5)
    @Named("mock")
    TransactionalEmailSender<Message, Void> mockSender() {
        return new TransactionalEmailSender<>() {

            @Override
            public String getName() {
                return "test";
            }

            @Override
            public Void send(Email email, Consumer emailRequest) throws EmailException {
                sentEmail = email;
                return null;
            }
        };
    }
}