The JavaMail API provides a platform-independent and protocol-independent framework to build mail and messaging applications. The JavaMail API is implemented as a Java platform optional package and is also available as part of the Java platform, Enterprise Edition.

You can use the following code to send a textual e-mail message to a single recipient from your Java program. Note that you need to download JavaMail API and put required jars into your classpath to be able to run this program.

 import java.io.*;
import javax.mail.*;
import javax.mail.internet.*;
import javax.activation.*;
    
public class SendApp {
  
    public static void send(String smtpHost, int smtpPort,
                            String from, String to,
                            String subject, String content)
                throws AddressException, MessagingException {

        // Create a mail session
        java.util.Properties props = new java.util.Properties();
        props.put("mail.smtp.host", smtpHost);
        props.put("mail.smtp.port", ""+smtpPort);
        Session session = Session.getDefaultInstance(props, null);
    
        // Construct the message
        Message msg = new MimeMessage(session);
        msg.setFrom(new InternetAddress(from));
        msg.setRecipient(Message.RecipientType.TO, new InternetAddress(to));
        msg.setSubject(subject);
        msg.setText(content);
    
        // Send the message
        Transport.send(msg);
    }
    
    public static void main(String[] args) throws Exception {
        // Send a test message
        send("hostname", 25, "This email address is being protected from spambots. You need JavaScript enabled to view it.", "This email address is being protected from spambots. You need JavaScript enabled to view it.",
             "Hello", "Hello, \n\n How are you ?");
    }
}