Last week I was having a problem receiving mail due to the fact that our domain name expired. This problem has been resolved, but now I am unable to send and receive email. After the domain name was resolved we were able to send and receive for 5 days until Sunday when the send and receive stopped. I think it is something to do with Sendmail. I restarted our mail server and it started. I also checked our MX record and it is pointing to the correct server.