canary mail

A plugin for Apple Mail that shows messages

IMAPCheck is a bundle for Mail.app

Plugin for Mail.app takes advantage of widescreen monitor.

A new open-source mail client for Mac OS X.

MailServe sets up a totally buzzword-compliant mail server on Mac OS X.

Block access to incoming and/or outgoing mail servers and websites

YAI (You Are Invited) is a plug-in for Apple Mail

Replace the sound warning of Mail

Assists administrators backing up mail settings and stores.

Adds labels & multi-colored flags to Mac Mail.