A frequent error that we often see with MX records is that a hostname is specified when it should not be. For example, ‘mail’ might be specified when ‘@’ should be.
The screen capture below shows the @ symbol for the hostname value. @ is equal to the ‘root’ or ‘apex’ of the domain, in other words, symbolizes a blank entry. The MX record configured below will allow email destined for user@testdomain.com to be sent to the server at mail.myserver.com.
If you put something else in the hostname field, such as ‘mail’, which is something we see quite often, that would mean that email would need to be addressed as user@mail.testdomain.com.
If you are having issues receiving mail to your ROOT domain and you do not have any MX records with the @ symbol as the hostname, that is most likely your issue.
If you require further assistance with troubleshooting MX records, submit a support ticket. We’re more than willing to take a look at your configuration.