Jakarta Commons Cookbook

10.17. Checking a POP3 Mailbox

Problem

You need to check a POP3 mailbox.

Solution

Use Commons Net POP3Client to check a POP3 mailbox for incoming mail. The following example connects to the POP3 server www.discursive.com, logs in as [e-mail], and prints each message in the mailbox:

import org.apache.commons.io.CopyUtils;
import org.apache.commons.io.IOUtils;
import org.apache.commons.net.pop3.POP3Client;
import org.apache.commons.net.pop3.POP3MessageInfo;

POP3Client client = new POP3Client( );
client.connect("www.discursive.com");
client.login("[e-mail]", "secretpassword");
        
POP3MessageInfo[] messages = client.listMessages( );
for (int i = 0; i < messages.length; i++) {
    int messageNum = messages[i].number;
    System.out.println( "************* Message number: " + messageNum );
    Reader reader = client.retrieveMessage( messageNum );
    System.out.println( "Message:\n" + IOUtils.toString( reader ) );
    IOUtils.closeQuietly( reader );
}
        
client.logout( );
client.disconnect( );

This example calls client.listMessage() to get an array of POP3MessageInfo objects. Each message is retrieved using the message number contained in each POP3MessageInfo. To retrieve the contents of an individual message, the message number is passed to retrieveMessage() , which returns a Reader from which the message body is read. The previous example prints the contents of a POP3 mailbox, as shown below:

************* Message number: 1 Message: Return-Path: <[e-mail]> X-Original-To: ...