mutt.

The traditional whine: "But everybody uses HTML!"

The solution:

in .mailcap:

text/html; lynx -dump %s; copiousoutput; nametemplate=%s.html

In .muttrc:

auto_view text/html application/x-gunzip text/calendar

alternative_order text/plain text text/html application/postscript

mutt can be used as a pure IMAP client or to read local mail delivered to mboxes or maildirs.

If you are the sort of person who builds up 250,000 messages on your IMAP server, guess what: mutt handles it better than any other client.

mutt is not point and click. mutt is usable by people who can read, and is powerful for people who can spend twenty minutes reading the docs.