Mac Mail can send but cannot receive mail.

I have been in contact with my Verizon Technical support. There is no problem at their end but my Mac Mail account can send but not receive mail. This has happened three times in the past month. Each previous time, Verizon found a problem, locally, at their end and within a few hours it was corrected.

This time the problem was passed upline to the most senior tech people. They have told me that there must be a registration problem with Mac Mail and I should contact Apple.

I have tried connection doctor without success.

If anyone knows a solution, I will start here before contacting apple support.

Mary Lou