Nokia Lumia 610 - How do I configure a non-standard port for e-mail server on my Lumia phone?

You can add port number to end of server name in the following way:

Go to Settings > select email + accounts > Select email account which server name you are editing.

Scroll down to the Incoming mail server (or Outgoing mail server) and modify the port number. For example mail.myemailserver.com:587, if the port number is 587.