| 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 Maildirmailbox 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 mboxmailbox 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. |