I've tried answers given on this site. Mail>Preferences>Account>Edit Server List etc. Tried re-entering the information (which is unchanged and correct.) Default ports are 25, 465, and 587. Changing to 465 made no difference.
This is happening more and more frequently, and then suddenly it'll correct itself. Extremely frustrating. Right now the list shows both servers are Offline. Why that should be, I don't know.
Any help greatly appreciated.
Mail 7.3; Mavericks; MacBook Pro