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.