I was always a user of Microsoft Entourage on my mac, having come from a PC background, it just felt right – having all my emails, names and dates was really useful. But recently I changed, and moved all my email from there to Apple’s own Mail program.
Mail is great, it’s simple for what I need and does it all well, except for a few minor things and these can be rectified or enhanced by the use of a plugin. There are a ton of these and they’re all Leopard compatible, unless otherwise stated.
SpamSieve – Spam filter (Commerical) In my opinion, it’s the best out there.
Related Mail – Displays related messages to viewed email (beta)
Mail Followup – Allows you to compose (and then send) a quoted version of the original message to all of the original recipients, keeping the To, Cc and Bcc addresses exactly as they appeared in the original message.
Letterbox – It rearranges the interface into three vertical columns.
And the rest:
OMiC – If you deal with a lot of Microsoft Outlook winmail.dat files, this is for you (Commercial)
Mailboxer – Automatically makes Smart Mailboxes for your address book contacts
Event Maker”:http://www.mamooba.com/EventMaker – Event Maker allows you to create normal and all-day events and To Dos from a selected message in Mail.app or from scratch using quick launch scripts