I am trying out Mail.app again – to see if some the issues I had in the past have been corrected in Leopard. Somehow, it just doesn’t seem to work right. I installed GPGMail (which is still beta for Leopard) and mostly got that working, except that for every key in my GPGKeyring it says that the key is invalid and there is no signing date (they all work fine in Enigmail…). Also, I set Mail.app to use the Trash folder for trash and the Sent folder for sent items, the Drafts folder for drafts and the Junk folder for junk mail. Seemed straightforward. Until I shut down Mail.app and reopened it. The trash and sent mail were still correctly mapped, but the Drafts folder was gone and no matter what I tried the Junk folder would not map to junk mail. Thankfully I didn’t have anything in the Drafts folder at the time! What a pain! So any junk mail I get is marked as junk (but I mostly have to do it myself – I am used to Thunderbird catching the majority of the stuff that spamassassin didn’t mark) but it stays in the inbox. That’s because Mail.app doesn’t know that the Junk folder is the junk folder. Even after I tried again (and again, and again) with the Mailbox > Use Folder As > Junk.
If I can get Mail.app to properly map the Drafts and Junk folders again I will likely try it on for a full week or two and see how I feel about it. If I can’t get it over that hurdle, however, forget it.