Spring Boot – Sending Email via SMTP

Spring Boot provides the ability to send emails via SMTP using the JavaMail Library. Here we will be illustrating step-by-step guidelines to develop Restful web services that can be used to send emails with or without attachments. In order to begin with the steps, let us first create a Spring Boot project using Spring Initializer.

Implementation:

Step 1: Adding the spring-boot-starter-mail dependency in pom.xml.

XML

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-mail</artifactId>
</dependency>

This dependency is a starter for using JavaMail and can be considered as Spring Framework’s email sending support

Step 2: Setting up Application.properties file with configurations required for using Gmail SMTP server.

spring.mail.host=smtp.gmail.com
spring.mail.port=587
spring.mail.username=<Login User to SMTP server>
spring.mail.password=<Login password to SMTP server>
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true

The Gmail Id used to login into your Gmail account can be provided as the username. For password generation, 2-step verification needs to be enabled for your account as follows:

Following that, AppPassword needs to be created using the following path:

Login to Gmail 
    -> Manage your Google Account 
        -> Security 
            -> App Passwords 
                -> Provide your login password 
                    -> Select app with a custom name 
                        -> Click on Generate

Step 3: Creating EmailDetails class that contains fields such as recipient, msgBody, subject, and attachment.

Java

// Java Program to Illustrate EmailDetails Class

package com.SpringBootEmail.Entity;

// Importing required classes
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

// Annotations
@Data
@AllArgsConstructor
@NoArgsConstructor

// Class
public class EmailDetails {

    // Class data members
    private String recipient;
    private String msgBody;
    private String subject;
    private String attachment;
}

Step 4: Creating interface EmailService and implementing class EmailServiceImpl of service layer.

The EmailService interface defines two methods:

1. String sendSimpleMail(EmailDetails details): This method can be used to send a simple text email to the desired recipient.
2. String sendMailWithAttachment(EmailDetails details): This method can be used to send an email along with an attachment to the desired recipient.

The Interface and service implementation class is as shown below in example as follows: 

File: EmailService.java

Java

// Java Program to Illustrate Creation Of
// Service Interface

package com.SpringBootEmail.service;

// Importing required classes
import com.SpringBootEmail.Entity.EmailDetails;

// Interface
public interface EmailService {

    // Method
    // To send a simple email
    String sendSimpleMail(EmailDetails details);

    // Method
    // To send an email with attachment
    String sendMailWithAttachment(EmailDetails details);
}

JavaMailSender interface of JavaMail API is used here to send simple text email. 

To send a more sophisticated email with an attachment, MimeMessage can be used. MimeMessageHelper works as a helper class for MimeMessage to add the attachment and other details required to send the mail.

File: EmailServiceImpl.java

Java

// Java Program to Illustrate Creation Of
// Service implementation class

package com.SpringBootEmail.service;

// Importing required classes
import com.SpringBootEmail.Entity.EmailDetails;
import java.io.File;
import javax.mail.MessagingException;
import javax.mail.internet.MimeMessage;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.core.io.FileSystemResource;
import org.springframework.mail.SimpleMailMessage;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.stereotype.Service;

// Annotation
@Service
// Class
// Implementing EmailService interface
public class EmailServiceImpl implements EmailService {

    @Autowired private JavaMailSender javaMailSender;

    @Value("${spring.mail.username}") private String sender;

    // Method 1
    // To send a simple email
    public String sendSimpleMail(EmailDetails details)
    {

        // Try block to check for exceptions
        try {

            // Creating a simple mail message
            SimpleMailMessage mailMessage
                = new SimpleMailMessage();

            // Setting up necessary details
            mailMessage.setFrom(sender);
            mailMessage.setTo(details.getRecipient());
            mailMessage.setText(details.getMsgBody());
            mailMessage.setSubject(details.getSubject());

            // Sending the mail
            javaMailSender.send(mailMessage);
            return "Mail Sent Successfully...";
        }

        // Catch block to handle the exceptions
        catch (Exception e) {
            return "Error while Sending Mail";
        }
    }

    // Method 2
    // To send an email with attachment
    public String
    sendMailWithAttachment(EmailDetails details)
    {
        // Creating a mime message
        MimeMessage mimeMessage
            = javaMailSender.createMimeMessage();
        MimeMessageHelper mimeMessageHelper;

        try {

            // Setting multipart as true for attachments to
            // be send
            mimeMessageHelper
                = new MimeMessageHelper(mimeMessage, true);
            mimeMessageHelper.setFrom(sender);
            mimeMessageHelper.setTo(details.getRecipient());
            mimeMessageHelper.setText(details.getMsgBody());
            mimeMessageHelper.setSubject(
                details.getSubject());

            // Adding the attachment
            FileSystemResource file
                = new FileSystemResource(
                    new File(details.getAttachment()));

            mimeMessageHelper.addAttachment(
                file.getFilename(), file);

            // Sending the mail
            javaMailSender.send(mimeMessage);
            return "Mail sent Successfully";
        }

        // Catch block to handle MessagingException
        catch (MessagingException e) {

            // Display message when exception occurred
            return "Error while sending mail!!!";
        }
    }
}

Step 5: Creating a Rest Controller EmailController which defines various API for sending email.

Java

// Java Program to Create Rest Controller that
// Defines various API for Sending Mail

package com.SpringBootEmail.controller;

// Importing required classes
import com.SpringBootEmail.Entity.EmailDetails;
import com.SpringBootEmail.service.EmailService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

// Annotation
@RestController
// Class
public class EmailController {

    @Autowired private EmailService emailService;

    // Sending a simple Email
    @PostMapping("/sendMail")
    public String
    sendMail(@RequestBody EmailDetails details)
    {
        String status
            = emailService.sendSimpleMail(details);

        return status;
    }

    // Sending email with attachment
    @PostMapping("/sendMailWithAttachment")
    public String sendMailWithAttachment(
        @RequestBody EmailDetails details)
    {
        String status
            = emailService.sendMailWithAttachment(details);

        return status;
    }
}

Step 6: Running the Spring Boot Application and hitting http://localhost:8080/sendMail to send a simple email

Mail received on Gmail is as follows:

Step 7: Running the Spring Boot Application and hitting http://localhost:8080/sendMailWithAttachment to send an email along with an attachment.

Mail received on Gmail is as follows: