We are co-existing between 2010 and 2013.
I switched my relay connector from 2010 to 2013 and my POP3 accounts couldn't connect.
I started the 2 POP services and verified firewall rules.
What else am I missing?
Here is one of the errors sent to me.
Also saw a few this.
The account 'domain\services' provided valid credentials, but it does not have submit permissions on SMTP Receive connector 'Default Frontend EXCH01'; failing authentication.
This is my relay connector security
same way on 2010 and 2013
update
as the emails come rolling in I believe the problem is authentication and not just POP3