Best Practices

Reading messages from an IMAP server is similar to reading messages from a POP3 server. With IMAP, however, the JavaMail API provides methods to create and manipulate folders and transfer messages between them. If you use an IMAP server, you can implement a full-featured, Web-based mail client with much less code than if you use a POP3 server. With POP3, you must provide code to manage a message store through your application server, possibly using a database or file system to represent folders.

One of J2EE's objectives is portability, and it always recommends a declarative approach over a programmatic approach to avoid hardcoding parameters. Avoid the programmatic approach as much as possible. Create and configure the Session object in a JNDI service as an administered object, so that you can tune it or change its parameters without changing any code.

It's always more efficient to use a shared Session object among all your components, even if you're working with mail sessions for multiple user mailboxes.