Packages 
Package Description
gnu.mail.providers.imap
This is a provider for the Internet Message Access Protocol, version 4rev1 (IMAP4rev1), as detailed in RFC 3501.
gnu.mail.providers.maildir
This is a provider for Dan Bernstein's Maildir mailbox format, used primarily by the qmail MTA, and also by some MUAs such as mutt.
gnu.mail.providers.mbox
This is a provider for the UNIX mbox mailbox file format, used by many 3rd-party MUAs including Netscape, Mozilla, mutt, elm, and pine.
gnu.mail.providers.nntp
This is a provider for the Network News Transfer Protocol (NNTP), as detailed in RFC 977.
gnu.mail.providers.pop3
This is a provider for the Internet Post Office Protocol, version 3 (POP3), as detailed in RFC 1939.
gnu.mail.providers.smtp
A provider for the Simple Mail Transfer Protocol (SMTP), as detailed in RFC 2821, including support for ESMTP service extensions.
gnu.mail.util  
javax.mail
Classes modelling a mail system.
javax.mail.event
Event objects and listener interfaces for JavaMail.
javax.mail.internet
Classes modelling Internet mail systems.
javax.mail.search
Search expressions for executing searches on the messages in a folder.