Re: @Angela Taylor
"So if an email server tries to send an email, and there's no MX record the email still gets sent?"
Potentially yes. There is a section of the RFC for smtp/email which refers to "fallback to A" meaning that if there is no MX record but there is a DNS entry for the domain with an A record then the A record address should be treated as a mail server and attempt to send the message to it. That of course may not work but in some cases it can, admittedly it wouldn't of helped in this case.
It is my understanding though that not all email systems implement the "fallback to A" process, be that by design or oversight.
Biting the hand that feeds IT
