I have my AT&T cellular through Tracfone. Ever since the migration, I've been unable to access my POP3 email via cellular. I just borrowed a friend's phone, set up my email account, and accessed my POP3 email just fine via cellular. That friend also has wireless service with AT&T, but directly with AT&T (not through Tracfone, like me). Her phone is the same phone as mine, too (iPhone 5s).
This seems like a problem with my AT&T account setup through Tracfone. I'd like to verify that. I'm trying to hear from anyone who is successfully (or unsuccessfully) accessing their Verizon (AOL) email account using POP3 and an MVNO. Preferably Tracfone, but it doesn't matter.