Active Exchange services, see Add Hosted Services, client software/hardware that supports TLS encryption.
Exchange 2013 POP3 Settings
|Encryption: SSL encryption is required.|
|POP3 Port: 995|
|SMTP Server ex13.myhostedservice.com|
|SMTP Port: 587|
|SMTP Encryption: TLS* encryption is required.|
|SMTP Authentication: Yes, same as incoming server|
*Note that the outgoing, SMTP, server uses Transport Layer Security (TLS) to transport mail. Not all mail clients, nor hardware (copiers, scanners) support TLS. TLS in short is a standard protocol that's used to provide secure Web communications on the Internet or intranets. It enables clients to authenticate servers or optionally, servers to authenticate clients. It also provides a secure channel by encrypting communications. TLS is the latest version of the Secure Sockets Layer (SSL) protocol. If your device does not support TLS we recommend you setup a split domain configuration.