JavaMail API Part 4 - Using secured protocol

There are many security measures we can implement into the system. We will take a special case of gmail which uses STARTTLS. STARTTLS is an extension to plain text communication protocols, which offers a way to upgrade a plain text connection to an encrypted (TLS or SSL) connection instead of using a separate port for encrypted communication.

Here is the code for sending email using host which implements STARTTLS.

package com.test;

import java.util.Properties;

import javax.activation.DataHandler;

import javax.activation.DataSource;

import javax.activation.FileDataSource;

import javax.mail.Message;

import javax.mail.MessagingException;

import javax.mail.Multipart;

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 SendMail {

   public static void main(String[] args) {

      String host = "smtp.gmail.com";

      String from = "sender@gmail.com";

      String pass = "sender's password";

      Properties props = System.getProperties();

      props.put("mail.smtp.starttls.enable", "true"); // added this line

      props.put("mail.smtp.host", host);

      props.put("mail.smtp.user", from);

      props.put("mail.smtp.password", pass);

      props.put("mail.smtp.port", "587");

      props.put("mail.smtp.auth", "true");

      String[] to = {"recipient1@abc.com, recipient2@abc.com"};

      String fileAttachment = "F:\\emoticons\\yawn.gif";

      Session session = Session.getDefaultInstance(props, null);

      MimeMessage message = new MimeMessage(session);

      try {

         message.setFrom(new InternetAddress(from));

         InternetAddress[] toAddress = new InternetAddress[to.length];

         // To get the array of addresses

         for( int i=0; i < to.length; i++ ) { // changed from a while loop

            toAddress[i] = new InternetAddress(to[i]);

         }

         for( int i=0; i < toAddress.length; i++) { // changed from a while loop

            message.addRecipient(Message.RecipientType.TO, toAddress[i]);

         }

         message.setSubject("sending in a group");

         // create the message part 

         MimeBodyPart messageBodyPart = new MimeBodyPart();

         //fill message

         messageBodyPart.setText("Hi");

         Multipart multipart = new MimeMultipart();

         multipart.addBodyPart(messageBodyPart);

         // Part two is attachment

         messageBodyPart = new MimeBodyPart();

         DataSource source = new FileDataSource(fileAttachment);

         messageBodyPart.setDataHandler(new DataHandler(source));

         messageBodyPart.setFileName(fileAttachment);

         multipart.addBodyPart(messageBodyPart);

         // Put parts in message

         message.setContent(multipart);

         Transport transport = session.getTransport("smtp");

         transport.connect(host, from, pass);

         transport.sendMessage(message, message.getAllRecipients());

         transport.close();

      } catch (AddressException e) {

         e.printStackTrace();

      } catch (MessagingException e) {

         e.printStackTrace();

      }
   }
}

JavaMail API Part 3 - Send attachment in email

Here is an example to send an email with attachment from your machine.

We assume that mail server is running on localhost and is connected to internet to send email.



For prerequisites please refer to my previous article on JavaMail API.

// File Name SendFileEmail.java



import java.util.*;

import javax.mail.*;

import javax.mail.internet.*;

import javax.activation.*;



public class SendFileEmail

{

   public static void main(String [] args)

   {

    

      // Recipient's email ID needs to be mentioned.

      String to = "abcd@gmail.com";

      // Sender's email ID needs to be mentioned

      String from = "web@gmail.com";

      // Assuming you are sending email from localhost

      String host = "localhost";

      // Get system properties

      Properties properties = System.getProperties();

      // Setup mail server

      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.

      Session session = Session.getDefaultInstance(properties);

      try{
         // Create a default MimeMessage object.

         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.

         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.

         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

         // Set Subject: header field

         message.setSubject("This is the Subject Line!");

         // Create the message part

         BodyPart messageBodyPart = new MimeBodyPart();

         // Fill the message

         messageBodyPart.setText("This is message body");

        

         // Create a multipar message

         Multipart multipart = new MimeMultipart();

         // Set text message part

         multipart.addBodyPart(messageBodyPart);

         // Part two is attachment

         messageBodyPart = new MimeBodyPart();

         String filename = "file.txt";

         DataSource source = new FileDataSource(filename);

         messageBodyPart.setDataHandler(new DataHandler(source));

         messageBodyPart.setFileName(filename);

         multipart.addBodyPart(messageBodyPart);

         // Send the complete message parts

         message.setContent(multipart );

         // Send message

         Transport.send(message);

         System.out.println("Sent message successfully....");

      }catch (MessagingException mex) {

         mex.printStackTrace();

      }

   }

}

Compile and run this program to send an HTML email:

$ java SendFileEmail

Sent message successfully....

User Authentication

If it is required to provide user ID and Password to the email server for authentication purpose then you can set these properties as follows:

props.setProperty("mail.user", "myuser");

props.setProperty("mail.password", "mypwd");

Rest of the email sending mechanism would remain as explained above.

JavaMail API Part 2 - Sending rich text in email

We send simple text in email in previous post in the series. In this article, we will send rich text. For rich text, MIME type is "text/html". The actual mail content is written in HTML. While sending email, HTML contents will be set and content type is set to "text/html".

We assume that mail server is running on localhost and is connected to internet to send email.

For prerequisites please refer to my previous article on JavaMail API.


Using this example, you can send as big as HTML content you like.

// File Name SendHTMLEmail.java



import java.util.*;

import javax.mail.*;

import javax.mail.internet.*;

import javax.activation.*;



public class SendHTMLEmail

{

   public static void main(String [] args)

   {

     

      // Recipient's email ID needs to be mentioned.

      String to = "abcd@gmail.com";

      // Sender's email ID needs to be mentioned

      String from = "web@gmail.com";

      // Assuming you are sending email from localhost

      String host = "localhost";

      // Get system properties

      Properties properties = System.getProperties();

      // Setup mail server

      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.

      Session session = Session.getDefaultInstance(properties);

      try{

         // Create a default MimeMessage object.

         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.

         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.

         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

         // Set Subject: header field

         message.setSubject("This is the Subject Line!");

         // Send the actual HTML message, as big as you like

         message.setContent("<h1>This is actual message</h1>", "text/html" );

         // Send message

         Transport.send(message);

         System.out.println("Sent message successfully....");

      }catch (MessagingException mex) {

         mex.printStackTrace();

      }

   }

}

Compile and run this program to send an HTML email:

$ java SendHTMLEmail

Sent message successfully....

JavaMail API Part 1 - Sending simple text email

There are many applications where system has to send an email to the user.

• Notification
• Validation
• Reporting
• Alarming etc

Sending email though look simple but it has many things to be considered like 

• Whether email is a rich text or simple text
• Whether email has attachment
• Email using authentication
• Emailing using secured protocols and mechanisms

Let's first take a simple case of sending a simple text email. We can write a simple standalone java application to send email. 

Prerequisites

We will need  JavaMail API and Java Activation Framework (JAF). You can download latest version from Oracle website.

• JavaMail API
• JAF

Download and unzip these files, in the newly created top level directories you will find a number of jar files for both the applications. You need to add mail.jar and activation.jar files in your CLASSPATH.

We will also need mail server to send an email. There are many open source mail server we can use or we can use inbuilt mail server from operating system. Let's assume that mail server is running on localhost.

Sending Text Email

Following is the code.

// File Name SendMail.java


import java.util.*;

import javax.mail.*;

import javax.mail.internet.*;

import javax.activation.*;



public class SendMail

{

   public static void main(String [] args)

   {
    

      // Recipient's email ID needs to be mentioned.

      String to = "abcd@gmail.com";

      // Sender's email ID needs to be mentioned

      String from = "web@gmail.com";

      // Assuming you are sending email from localhost

      String host = "localhost";

      // Get system properties

      Properties properties = System.getProperties();

      // Setup mail server

      properties.setProperty("mail.smtp.host", host);

      // Get the default Session object.

      Session session = Session.getDefaultInstance(properties);

      try{

         // Create a default MimeMessage object.

         MimeMessage message = new MimeMessage(session);

         // Set From: header field of the header.

         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.

         message.addRecipient(Message.RecipientType.TO, new InternetAddress(to));

         // Set Subject: header field

         message.setSubject("This is the Subject Line!");

         // Now set the actual message

         message.setText("This is actual message");

         // Send message

         Transport.send(message);

         System.out.println("Sent message successfully....");

      }catch (MessagingException mex) {

         mex.printStackTrace();

      }

   }

}

Compile and run this program to send a simple email:

$ java SendMail

Sent message successfully....

Sending Email to multiple recipient

If you want to send an email to multiple recipients then following methods would be used to specify multiple email IDs:

void addRecipients(Message.RecipientType type, Address [] addresses) MessagingException

Here is the description of the parameters:

• type: This would be set to TO, CC or BCC. Here CC represents Carbon Copy and BCC represents Black Carbon Copy. Example Message.RecipientType.TO
• addresses: This is the array of email ID. You would need to use InternetAddress() method while specifying email IDs