I just installed MS office 2016 professional plus, and am trying to add my two at&t email accounts(@bellsouth.net). When adding all the necessary info( name, email, password, settings etc.) and click OK, I get an error message that the username or password is incorrect. However, they both are correct. I do not know however, whether I should be entering the incoming and outgoing mail as POP or IMAP.

Could someone please help?