POP3 accounts are for recieving e-mail. If Scan Router PRO tries to recieve e-mail to deliver to a fax or something like that it will need POP3 information. Similar to the NIC fax unit on the 5510NF. If you don't need it to do POP3 recieveing and can turn it off, do that. The other option is to set up a "ghost" e-mail account to send the POP information to. SOME ISP's require POP authentication prior to allowing you to send SMTP e-mail. Some require POP and SMTP authentication and others require no authentication to send e-mail through their SMTP servers. There are so many variables to consider.
Hope that helps a little
Graham