For ages I had problem with the login name with the email system they have at work, Microsoft Exchange Server 2000. While it would work fine via the MAPI or web interfaces, I couldn't get it to work via POP3 or IMAP4. Searching online brought up the notion of using a special sequence as the login name,
domain\username\mailbox, so it'd be something like
geeksrv\Damien McKenna\dmckenna. Well, turned out that wasn't correct and today I finally got it, I needed to do
domain\ntloginname\exchangealias which ends up being completely different than the other one. Thought you admin-types might like to know.