In 10.2 Mail, the only AppleScripts you could run were found in the system wide Script Menu (and that is only if you decide to "install" it) In Panther Mail, as in Panther's Address Book, there is a Script Menu next to the Window Menu. Handy huh? Panther Mail's AppleScript Dictionary is also even bigger then 10.2's Mail.

Mail Scripts 2.0 (now final) are great additions to Mail's Script Menu. You should check them out if you have not already.

Mail's Junk Mail Filter has grown a lot since 10.2. Although I highly encourage you to turn if off, and install POPFile or SpamSieve. Both of these products do a much better job at classifying the SPAM then Mail's Junk Mail Filter, it is ineffective in comparison to POPFile or SpamSieve. Mail might be bayesian, but it is of another flavor of bayesian. I personally think Apple should buy Michael Tsai's SpamSieve and incorporate it into Mail.

But, if you do not want to install any 3rd party software to handle junk mail, at least use the Junk Mail Filter. Panther Mail adds a "trust junk mail headers" check box, which, BTW, can be manually added as a rule, if you know what the junk mail header looks like. But as Apple is great at making things easier to use, you now have that check box. Panther Mail also allows you to use your Address Book as a whitelist, meaning address in your Address Book are never spam. This can be hazardous in some cases, and I would be weary of using this option.

Being able to block the loading of images is a huge improvement, and a very nice feature of any email client.

As I said earlier, the Organize by Thread feature is wonderful. Being able to forward an entire thread is also cool. I know both Eudora and Mozilla Mail will show a thread, it is nice that now Mail has this capability.