How to Send Emails in Spring Boot Using SMTP (With and Without Attachments)

Sending emails is a common requirement in modern web applications — for things like user registration, password resets, or notifications. In this tutorial, we’ll walk through how to send emails in a Spring Boot application using SMTP, specifically with Gmail’s SMTP server, and demonstrate how to send both plain emails and emails with attachments.

📺 Video Demo

If you prefer watching over reading, here’s a full demo of this tutorial in action:

📁 GitHub Repo 

Want the complete working code? Clone the GitHub link provided below which contains all the source code.

Source Code GitHub Link: https://github.com/TheDipDeveloper/Spring-Boot-Sending-Email

🧰 Prerequisites

• Java 17 or above

• Maven

• Spring Boot 3.x

• A Gmail account 

🚀 Step 1: Add Spring Boot Mail Dependency

First, add all the required dependency on pom.xml file

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

    <dependency>
       <groupId>org.projectlombok</groupId>
       <artifactId>lombok</artifactId>
       <optional>true</optional>
    </dependency>
    <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-test</artifactId>
       <scope>test</scope>
    </dependency>
</dependencies>

⚙️ Step 2: Configure SMTP in application.properties

Configure your SMTP settings in src/main/resources/application.properties. 

Here’s an example for Gmail:

spring.application.name=java-mail-service

spring.mail.host=smtp.gmail.com
spring.mail.port=587
spring.mail.username=emailId
spring.mail.password=16DigitAppPassword
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true

💡 Important: You’ll need to generate an App Password for your account.

📦 Step 3: Create an Email Model

Create a simple class to hold the email request details.

package com.dipdeveloper.java_mail_service;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class EmailDetails {
    private String recipient;
    private String msgBody;
    private String subject;
    private String attachment;
}

🔧 Step 4: Build the Email Service

Create a service interface:

package com.dipdeveloper.java_mail_service;

public interface EmailService {
    String sendSimpleMail(EmailDetails details);
    String sendMailWithAttachment(EmailDetails details);
}

Then implement it:

package com.dipdeveloper.java_mail_service;

import java.io.File;

import jakarta.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;

@Service
public class EmailServiceImpl implements EmailService {

    @Autowired
    private JavaMailSender javaMailSender;

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


    public String sendSimpleMail(EmailDetails details) {
        try {
            SimpleMailMessage mailMessage = new SimpleMailMessage();
            mailMessage.setFrom(sender);
            mailMessage.setTo(details.getRecipient());
            mailMessage.setText(details.getMsgBody());
            mailMessage.setSubject(details.getSubject());
            javaMailSender.send(mailMessage);
            return "Email Sent Successfully.";
        } catch (Exception e) {
            e.printStackTrace();
            return "Error occur while Sending Mail";
        }
    }

    public String sendMailWithAttachment(EmailDetails details) {
        try {
            MimeMessage mimeMessage = javaMailSender.createMimeMessage();
            MimeMessageHelper mimeMessageHelper = new MimeMessageHelper(mimeMessage, true);
            mimeMessageHelper.setFrom(sender);
            mimeMessageHelper.setTo(details.getRecipient());
            mimeMessageHelper.setText(details.getMsgBody());
            mimeMessageHelper.setSubject(details.getSubject());
            FileSystemResource file = new FileSystemResource(new File(details.getAttachment()));
            mimeMessageHelper.addAttachment(file.getFilename(), file);
            javaMailSender.send(mimeMessage);
            return "Email sent Successfully with Attachment.";
        } catch (Exception e) {
            e.printStackTrace();
            return "Error occur while sending mail.";
        }
    }
}

🌐 Step 5: Expose an API Endpoint

Now create a REST controller to trigger these emails.

package com.dipdeveloper.java_mail_service;

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;

@RestController
public class EmailController {

    @Autowired
    private EmailService emailService;

    @PostMapping("/send")
    public String sendMail(@RequestBody EmailDetails details) {
        return emailService.sendSimpleMail(details);
    }

    @PostMapping("/sendWithAttachment")
    public String sendMailWithAttachment(@RequestBody EmailDetails details) {
        return emailService.sendMailWithAttachment(details);
    }
}

🧪 Testing the API

You can use Postman or curl to test the endpoints:

✅ Send Simple Email

 https://github.com/TheDipDeveloper/Spring-Boot-Sending-Email/blob/main/README.md

✅ Send Email with Attachment

 https://github.com/TheDipDeveloper/Spring-Boot-Sending-Email/blob/main/README.md

🎯 Conclusion

You’ve now built a Spring Boot application that can send both basic and attachment-based emails using SMTP. This is extremely useful for integrating email into your web apps — whether it’s for notifications, user onboarding, or customer support.

🔐 Security Tip

Don’t hardcode your email credentials! Use Spring Cloud Config, Vault, or environment variables for production.