When you run a POP3 email account in a Microsoft Exchange Server 2013 environment, the POP3 services intermittently stop. This causes users and applications not to send or receive email messages. However, after the administrator manually starts the POP3 services, users can send and receive email messages as expected.
This problem occurs because the proxy session for the POP3 Service is not handled correctly by Exchange Server.
Exchange Server 2013
To resolve this problem, install Cumulative Update 21 for Exchange Server 2013 or a later cumulative update for Exchange Server 2013.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Start and stop the POP3 services
Overview of POP3 and IMAP4 functionality
Learn about the terminology that Microsoft uses to describe software updates.