If I can expand on your "HTML mail from idiots" -- HTML mail from non-idiots is pretty much a non-issue. A textual document with minimal markup renders well in a standard console email client. It's when an idiot sends you a highly-formatted email which is all-but-unreadable as straight text, that you've got issues.
I'll add: the same highly-formatted emails are very likely to break horribly on handheld devices as well, which are pretty much limited to presenting a small amount of information with minimal formatting -- normal, italic, bold, and possibly some colored text.
And dittos on K9Mail.
For IMAP: offlineimap seems to be a good solution (though not so much on mobile).
Directories: really should be a solved problem by now. I still find myself generally maintaining my own .mail-aliases list though.
I also "love" when I receive "thank you for registering, click here to login", and after staring at the e-mail for a bit, seeing no links anywhere at all, I realize that the well-meaning-but-sadly-still-full-of-fail website operator that sent the message went to the trouble of providing a multipart/alternative with a text/plain body part, but implemented it as "strip the tags from the text/html part: that should be good enough".
(FWIW, I took the emphasis and subsequent wonkier smily to mean he was joking, and in fact have accidentally sent such emails in the past from his own website.)
I'll add: the same highly-formatted emails are very likely to break horribly on handheld devices as well, which are pretty much limited to presenting a small amount of information with minimal formatting -- normal, italic, bold, and possibly some colored text.
And dittos on K9Mail.
For IMAP: offlineimap seems to be a good solution (though not so much on mobile).
Directories: really should be a solved problem by now. I still find myself generally maintaining my own .mail-aliases list though.