By far the most common cause of email problems we see is, in fact, unrelated to email itself.
If your account has suddenly stopped receiving email but appears to be working correctly in every other way, there's a high probability that your hosting account is full.
When your disk space allocation is fully used, incoming email is unable to be delivered to you. It will remain in our mail queue and attempt to re-send for approximately four days, after which time it will be bounced back to the sender with a failure message.
How do I check if my account is full?
On the left-hand side of your cPanel are the "Disk Space Usage" and "Disk space available" figures. This will show you if your account has reached the limit. You will also be automatically emailed when your reach 80% of your limit, provided your cPanel contact email address is valid and working. We recommend using an offsite email address as your cPanel contact.
Why is my account full?
One reason we often see is in cases where a customer was unaware of their "catch-all mailbox". The catch-all mailbox comes by default with every account and while it can be very useful, it can also fill your account with SPAM email over time.
Email left accumulating on the server over time is the most common reason a hosting account will fill. Most email software has an option to "Delete Email from Server" once you've downloaded it. Setting this option will usually ensure that email doesn't build up on the server.
My account isn't full, and I still can't figure out why I'm not receiving email!
If you're unsure about anything, just let us know. We can look into the situation and send test emails through. Please be sure to specify exactly what email address(es) you're having trouble with and what, if any, error messages you're seeing. Any additional information you can provide will be helpful.