Do you support IMAP?

IMAP stands for Internet Message Access Protocol, and is a method of accessing electronic mail on a mail server. It offers several advantages over POP3 - including the ability to manage email in folders on and off the email server. We provide IMAP access for every email account. The IMAP server gives you the ability to use advanced email clients such as Outlook or Netscape Mail, supporting the advanced features of the IMAP protocol.

Make sure you have ident enabled and that you/your isp do not block it.

Port 143 must be open if you have a firewall.