在pom.xml中添加此依赖项

<!-- https://mvnrepository.com/artifact/com.sun.mail/javax.mail -->
<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.6.2</version>
</dependency>

使用这个方法

private boolean sendEmail(String messege, String subject, String email, String from,int otp,String password) {
    //Variable for gmail
    String host="smtp.gmail.com";
    //get the system properties
    Properties properties = System.getProperties();
    System.out.println("PROPERTIES "+properties);
    //setting important information to properties object
    //host set
    properties.put("mail.smtp.host", host);
    properties.put("mail.smtp.port","465");
    properties.put("mail.smtp.ssl.enable","true");
    properties.put("mail.smtp.auth","true");
    //Step 1: to get the session object..
    Session session=Session.getInstance(properties, new Authenticator() {
        @Override
        protected PasswordAuthentication getPasswordAuthentication() {              
            return new PasswordAuthentication(from, password);
        }
    });
    session.setDebug(true);
    //Step 2 : compose the message [text,multi media]
    MimeMessage m = new MimeMessage(session);
    try {
    //from email
    m.setFrom(from);
    //adding recipient to message
    m.addRecipient(Message.RecipientType.TO, new InternetAddress(email));
    //adding subject to message
    m.setSubject(subject);
    //adding text to message
    m.setText(messege);
    //send 
    //Step 3 : send the message using Transport class
    Transport.send(m);
    System.out.println("Sent success...................");
    }catch (Exception e) {
        e.printStackTrace();
        return false;
    }
    return true;
}

您还阅读了javamail api文档