Packages 
Package Description
com.sun.activation.registries  
com.sun.mail.auth
This package includes internal authentication support classes and SHOULD NOT BE USED DIRECTLY BY APPLICATIONS.
com.sun.mail.gimap
An EXPERIMENTAL IMAP protocol provider that supports the Gmail-specific IMAP protocol extensions .
com.sun.mail.gimap.protocol  
com.sun.mail.handlers
This package includes internal data handler support classes and SHOULD NOT BE USED DIRECTLY BY APPLICATIONS.
com.sun.mail.iap
This package includes internal IMAP support classes and SHOULD NOT BE USED DIRECTLY BY APPLICATIONS.
com.sun.mail.imap
An IMAP protocol provider for the JavaMail API that provides access to an IMAP message store.
com.sun.mail.imap.protocol
This package includes internal IMAP support classes and SHOULD NOT BE USED DIRECTLY BY APPLICATIONS.
com.sun.mail.pop3
A POP3 protocol provider for the JavaMail API that provides access to a POP3 message store.
com.sun.mail.smtp
An SMTP protocol provider for the JavaMail API that provides access to an SMTP server.
com.sun.mail.util
Utility classes for use with the JavaMail API.
com.sun.mail.util.logging
Contains JavaMail™ extensions for the Java™ platform's core logging facilities.
javax.activation
The JavaBeans(TM) Activation Framework is used by the JavaMail(TM) API to manage MIME data.
javax.mail
The JavaMail™ API provides classes that model a mail system.
javax.mail.event
Listeners and events for the JavaMail API.
javax.mail.internet
Classes specific to Internet mail systems.
javax.mail.search
Message search terms for the JavaMail API.
javax.mail.util
JavaMail API utility classes.