mail clients

["Jim B" <vader@conflict.net>]

Hi all.  Is there a good POP3 and/or IMAP4 client (console or GUI, doesn't
matter) that supports multiple accounts with easy switching between them...
and that can filter based on the "account" concept rather than just on
headers?

If I'm not making sense, I'm looking for something for Linux that can do
what MS Outlook Express can do.  Here's an example:

One account is username "joe" and another account is username "tom."

Someone sends to joe and the mail is filtered into his mailbox... meanwhile,
tom's mail is filtered into his mailbox.  BUT, if someone BCCs joe, his
username will not appear in the headers... therefore, header-based filtering
will be useless.  The client needs to be able to filter the mail into the
"joe" mailbox despite the fact that his address is not in the headers.  The
idea is simple, it just needs to know "From what account did I download this
message?" in order to be able to direct it appropriately, despite what may
be in the headers of the message.

Anyone know of such a client?  Pine's "roles" don't cut it as a single login
cannot access multiple e-mail accounts.  Also, procmail doesn't come into
the picture because the filtering rules must be client-based so that all
these mail accounts can be accessed from a single terminal login session,
rather than by logging out and then back into another session.

Thanks!!!