Mailsmith -- I'm guessing -- will probably never include html formatting. The people for whom this email client was built don't value html formatting. I have turned email formatting off in every client I've used. It's still there -- via safari -- if you need it. Where html formatting should be, in a browser.

Mailsmith is a solid email client for people who receive a ton of email. Folder based filters are brilliant. Search capabilities are outstanding. Scriptability is great. Anti-Spam features are unbeatable. However, I think it will be several versions yet before it is THE Mac os x email client for power users. I'd like to see fast searching like Mail/Entourage have, imap access, more interaction with the server (ability to automate deleting files from the server), and interface improvements -- barebones seems religiously minimalistic in their interfaces -- but an email client is different than a text editor. It needs to alert you and give you feedback and direct your attention more, which means using icons. An icon/graphic gives far more information in a smaller amount of space than a word.
I'd also like to see speed improvements and more threading (or whatever it is that causes the app to be unavailable as it pulls a large attachment off of the server).
Still, in these days of spam and multiple accounts, I'm finding it hard to go back to entourage, and apple's mail is no competition whatsoever.

Yes, it's spendy, I think it'd do far better as a $60 app, but if you're wasting an hour a day sorting through messages and trying to cope with your email client, the price seems like a lot less and the value a lot more.