Symptoms

When attempting to add a new environment field for mail server in K2 Studio, an error "Enter a valid server name" appears. Unable to add the environment field. The server name I am trying to add is smtp.denallix.com:587
 

Diagnoses

K2 Studio will perform a validation check on the Server Name when you attempt to add the field. It does not accept server name with port definition.
 

Resolution

Removing the port definition from the server name will allow you to add the field in K2 Studio.

Alternatively, you can do it through K2 workspace > Management Console > Environment Library.