Email Software for Mac

I am looking for an email client to be able to perform certain actions, but have been unable to find one.
I want it to be able to automatically "sort" incoming emails. If the email contains the word "macbook" and "apple" it should automatically transfer it to a folder I created.
Eudora had an option where I could sort incoming emails, but only by the subject (not body) of the email. Please let me know where I can get an email client like this! Thanks!

Kyle

You can set up rules like that for Mail.
Mail comes with OS X.

How to Manage Email With Rules in Apple Mail.app | eHow.com

Thunderbird does this too, AND Thunderbird is transparently multi platform, due to the fact that it used the industry standard MBX mailbox format.

I have used Thunderbird for years, on PCs, Linux and Macs. It works everywhere, pretty much the same, and ensures that your all important email is not locked into one application's format (Mail).

This is not Mac Mail bashing - just pointing out the benefits of Thunderbird. Clearly I am a fan!

The problem with both Thunderbird and Mail is neither of them receive regular updates anymore... I've been waiting on Thunderbird 3 for ages.