Do you want to use POP3 with BPOS? Not a problem, check this video out http://blogs.technet.com/b/msonline/archive/2011/02/14/enable-pop3-in-microsoft-exchange-online-mailboxes.aspx
In the latest BPOS support video, we explore enabling POP3 in Microsoft Exchange Online Mailboxes. POP3 stands for Post Office Protocol 3, and is the latest version of the standard protocol to receiving email. POP3 is found in most popular email offerings including Outlook. By default POP3 is not enabled for Microsoft Online users, and this support video will provide an overview on how to enable and disable the POP3 protocol for mailboxes.