Mail troubles

Emails don’t seem to be arriving from my server to the mac; when i open Mail account info, “Show messages: all messages on POP server” shows a list of emails; when i “Get All Mail” nothing turns up (i.e. none of the ones shown in "Show Messages on POP server". It seems there’s some sort of ‘blockage’ stopping mail at server getting through to Mail inbox. Any thoughts?

I have my own domain. Server assures me nothing wrong at his end; i can also look up on Webmail and all emails are shown. I have of course quit and restarted; turned off and unplugged.

Haven't really done/loaded anything new lately. OS X 10.10.3