I have a WM5 device, and use the Pocket Outlook for a couple of DH accounts.
I configured them for IMAP, not POP.
In the username block, I have my email@example.com, and I manually entered the password and checked the box to save the password.
Incoming and outgoing mail servers are mail.mydomain.com.
Under Options for the mail servers, option screen 1 had nothing checked, on option screen 2 Outgoing mail requires authorization is checked, and on option screen 3 I set mine to Get full copy of messages, and only get attachments if smaller than 25KB.
I send and receive e-mail from these accounts on the handheld, almost daily.
Before trying to configure Pocket Outlook, I would make sure you can use the webmail interface to access those mailboxes, just to be sure you have the right password.