The majority of my emails via @mac.com are not being delivered
The majority of my emails via @mac.com are not being delivered. I have rebuilt the inbox a few times to no avail. I have also logged in to my account via Safari but I am still unable to receive the messages. I need my business messages. Perhaps gmail is a better solution. How can I recover lost messages? A few times I can see messages appearing and then they disappear. What is the issue?
MacBook Pro (Retina, 13-inch, Late 2012), OS X El Capitan (10.11.3)