People who send me an email get a message back saying my inbox is full. I do actually receive the email.
Is this a virus? How do I stop this happening?
Are there any attachments to the emails the others receive? If yes, what kind of attachments? If it is
If there are no attachments, then clear out your inbox, it's not a virus. It's you not cleaning out your inbox.
Each user on a server is assigned a certain amount of disk space. Yours is full. Delete unwanted items and then empty the trash, or call your provider and ask them to increase your quota.
You're probably getting some, but not all, of your incoming mail.
Say someone sends you a 42k email message and your account has just enough room to write the message to disk: the server will acknowledge receipt of the message and the sender will not receive a bounce. Three minutes later, when another message arrives but there's no room left to write it, the server returns an error saying your inbox is full. Later, you check your mail and create a little more space. Rinse and repeat.