Mailhub is an extension to Apple’s built in mail application ( Mail.app )

This plugin was written by the fine folks at Dervish Software.  Once installed, it is configured via Mail’s Preferences

Mailhub has become one of the most important pieces of software on our computers.

• Send and File: Every time a message is sent, Mailhub offers to auto-file the message and it’s reply into its proper folder
• Typing Command Return can file a message where it belongs without any mouse action.
• Quickly file all messages from a given sender or thread in one mouse action.
• Displays who sent messages were sent to, regardless of which folder the message is stored.

There are more features, of course, as the project is being actively developed by the developers.

Thank you Dervish Software, I simply love easily filing messages in Apple’s Mail application!

PS If you used to use Eudora for your mail client, welcome home.
Mailhub is a great replacement for such a fine email application.