You can use Springboot to send out emails. All you need is access SMTP server. You can then use the JavaMailSender interface to send emails out.

Add dependency

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

Add email SMTP server configuration settings to application.properties

#mail
spring.mail.host=smtp.gmail.com
spring.mail.username=username
spring.mail.password=password
spring.mail.port=587
spring.mail.properties.mail.smtp.auth=true
spring.mail.properties.mail.smtp.starttls.enable=true
spring.mail.properties.mail.debug=true
spring.mail.properties.mail.sender=senderEmail@gmail.com

EmailService

import java.io.IOException;

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.ClassPathResource;
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 EmailServiceImp implements EmailService {

    @Autowired
    private JavaMailSender mailSender;
    
    
    // This is for aws ses mail. Sender email needs to be verified first before using it as a sender email.
    @Value("${spring.mail.properties.mail.sender}")
    private String sender;

    @Override
    public boolean sendSimpleMail(String to, String subject, String msg) {
        SimpleMailMessage simpleMailMessage = new SimpleMailMessage();
        simpleMailMessage.setTo(to);
        simpleMailMessage.setSubject(subject);
        simpleMailMessage.setText(msg);
        simpleMailMessage.setFrom(sender);
        try {
            mailSender.send(simpleMailMessage);
            return true;
        } catch (Exception e) {
            System.out.println("Exception, send. msg: " + e.getMessage());
            return false;
        }
    }

    @Override
    public boolean sendAttachmentMail(String to, String subject, String msg, String attachmentPath) {
        MimeMessage message = mailSender.createMimeMessage();

        try {
            MimeMessageHelper helper = new MimeMessageHelper(message, true);
            helper.setTo(to);
            helper.setSubject(subject);
            helper.setText(msg);
            helper.setFrom(sender);
            ClassPathResource attachment = new ClassPathResource(attachmentPath);
            helper.addAttachment(attachment.getFile().getName(), attachment.getFile());
            mailSender.send(message);
            return true;
        } catch (MessagingException e) {
            System.out.println("Exception, send. msg: " + e.getMessage());
            return false;
        } catch (IOException e) {
            System.out.println("Exception, send. msg: " + e.getMessage());
            return false;
        }

    }

    
    /*
     * It's recommended that when sending html emails that you use table to structure and style
     * your email.
     * */
    @Override
    public boolean sendHtmlMail(String to, String subject, String msg) {
        MimeMessage message = mailSender.createMimeMessage();

        try {
            MimeMessageHelper helper = new MimeMessageHelper(message, true);
            helper.setTo(to);
            helper.setSubject(subject);
            helper.setText(msg, true);
            helper.setFrom(sender);
            mailSender.send(message);
            return true;
        } catch (MessagingException e) {
            System.out.println("Exception, send. msg: " + e.getMessage());
            return false;
        }
    }

    
    /*
     * It's recommended that when sending html emails that you use table to structure and style
     * your email.
     * */
    @Override
    public boolean sendHtmlWithInlineImageMail(String to, String subject, String msg, String logoPath) {
        MimeMessage message = mailSender.createMimeMessage();

        try {
            MimeMessageHelper helper = new MimeMessageHelper(message, true);
            helper.setTo(to);
            helper.setSubject(subject);
            helper.setText(msg,true);
            helper.setFrom(sender);
            // cid:log
            helper.addInline("logo", new ClassPathResource(logoPath));
            
            mailSender.send(message);
            return true;
        } catch (MessagingException e) {
            System.out.println("Exception, send. msg: " + e.getMessage());
            return false;
        }
    }

}

Source code on Github