This article provides a step-by-step guide on how to add attachments to an e-mail message to be sent via a SMTP server, using the JavaMail API. To understand how attachments are stored inside an e-mail message, let’s take a look at the following picture:

e-mail message structure

As we can see, a message comprises of a header and a body. The body must be of type Multipart for containing attachments. The Multipart object holds multiple parts in which each part is represented as a type of BodyPart whose subclass, MimeBodyPart – can take a file as its content.

The steps to create a multipart message with multiple parts are as follows:

Message message = new MimeMessage(session);
Multipart multipart = new MimeMultipart();

// creates body part for the message
MimeBodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setContent(message, "text/html");

// creates body part for the attachment
MimeBodyPart attachPart = new MimeBodyPart();

// code to add attachment...will be revealed later

// adds parts to the multipart
multipart.addBodyPart(messageBodyPart);
multipart.addBodyPart(attachPart);

// sets the multipart as message's content
message.setContent(multipart);

 

The MimeBodyPart class provides some convenient methods for attaching a file, but the way is different between JavaMail 1.3 and JavaMail 1.4.

With JavaMail 1.3, it requires writing the following code to add an attachment:

// JavaMail 1.3
MimeBodyPart attachPart = new MimeBodyPart();
String attachFile = "D:/Documents/MyFile.mp4";

DataSource source = new FileDataSource(attachFile);
attachPart.setDataHandler(new DataHandler(source));
attachPart.setFileName(new File(attachFile).getName());

multipart.addBodyPart(attachPart);

 

With JavaMail 1.4, adding an attachment is much simpler with the following new methods introduced in the MimeBodyPart class:

  •            void attachFile(File file)
  •            void attachFile(String filePath)

So the code with JavaMail 1.4 would look like this:

// JavaMail 1.4
MimeBodyPart attachPart = new MimeBodyPart();
String attachFile = "D:/Documents/MyFile.mp4";
attachPart.attachFile(attachFile);
multipart.addBodyPart(attachPart);

Banner will redirect to landing page with health and fitness courses.The code for JavaMail 1.3 still works in 1.4.

Now for a sample program, the following class, EmailAttachmentSender – implements a static method, sendEmailWithAttachments() – which can be used for sending an e-mail message with some attachments. This method requires the following parameters:

  •            For SMTP server information: host, port number, user name (e-mail address), and password.
  •            For e-mail message: recipient e-mail address, subject, and message.
  •            For attached files: an array of String for file paths.

Here is the code of the class EmailAttachmentSender:

package net.codejava.mail;

import java.io.IOException;
import java.util.Date;
import java.util.Properties;

import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.AddressException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;

public class EmailAttachmentSender {

	public static void sendEmailWithAttachments(String host, String port,
			final String userName, final String password, String toAddress,
			String subject, String message, String[] attachFiles)
			throws AddressException, MessagingException {
		// sets SMTP server properties
		Properties properties = new Properties();
		properties.put("mail.smtp.host", host);
		properties.put("mail.smtp.port", port);
		properties.put("mail.smtp.auth", "true");
		properties.put("mail.smtp.starttls.enable", "true");
		properties.put("mail.user", userName);
		properties.put("mail.password", password);

		// creates a new session with an authenticator
		Authenticator auth = new Authenticator() {
			public PasswordAuthentication getPasswordAuthentication() {
				return new PasswordAuthentication(userName, password);
			}
		};
		Session session = Session.getInstance(properties, auth);

		// creates a new e-mail message
		Message msg = new MimeMessage(session);

		msg.setFrom(new InternetAddress(userName));
		InternetAddress[] toAddresses = { new InternetAddress(toAddress) };
		msg.setRecipients(Message.RecipientType.TO, toAddresses);
		msg.setSubject(subject);
		msg.setSentDate(new Date());

		// creates message part
		MimeBodyPart messageBodyPart = new MimeBodyPart();
		messageBodyPart.setContent(message, "text/html");

		// creates multi-part
		Multipart multipart = new MimeMultipart();
		multipart.addBodyPart(messageBodyPart);

		// adds attachments
		if (attachFiles != null && attachFiles.length > 0) {
			for (String filePath : attachFiles) {
				MimeBodyPart attachPart = new MimeBodyPart();

				try {
					attachPart.attachFile(filePath);
				} catch (IOException ex) {
					ex.printStackTrace();
				}

				multipart.addBodyPart(attachPart);
			}
		}

		// sets the multi-part as e-mail's content
		msg.setContent(multipart);

		// sends the e-mail
		Transport.send(msg);

	}

	/**
	 * Test sending e-mail with attachments
	 */
	public static void main(String[] args) {
		// SMTP info
		String host = "smtp.gmail.com";
		String port = "587";
		String mailFrom = "your-email-address";
		String password = "your-email-password";

		// message info
		String mailTo = "your-friend-email";
		String subject = "New email with attachments";
		String message = "I have some attachments for you.";

		// attachments
		String[] attachFiles = new String[3];
		attachFiles[0] = "e:/Test/Picture.png";
		attachFiles[1] = "e:/Test/Music.mp3";
		attachFiles[2] = "e:/Test/Video.mp4";

		try {
			sendEmailWithAttachments(host, port, mailFrom, password, mailTo,
				subject, message, attachFiles);
			System.out.println("Email sent.");
		} catch (Exception ex) {
			System.out.println("Could not send email.");
			ex.printStackTrace();
		}
	}
}

NOTE: The JavaMail API requires JavaBeans Activation Framework (JAF) which is included in the JDK 6 and JDK 7. So if you are using JDK 5 or earlier version, you must download the JAF and add the activation.jar file to your classpath.

For Swing-based version of the sample program, see this tutorial: Swing application for sending e-mail (with attachments).

 

Recommended Book: JavaMail API

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