Problem receiving email using Mail on the Mac

Problem receiving email using Mail on the Mac

Today I've noticed that emails haven't been coming through on my Mac using Mail. Only noticed when I checked my iPhone at lunchtime and I had 15 unread emails that didn't appear on my Mac. Tried get new messages but that doesn't work, the only option I have is to quit Mail completely and then relaunch it, that then prompts it to download any new emails.

Anyone else having the same problem? Has something changed or do I need to change anything to get it working again?