CNAME / A with MX Records

Stumbled into an issue again today that has come up a few times for me, so I figured I will right out the reason for this as a friendly reminder.

The Scenario:

I have a CNAME Record "" pointing to "".  Now I want to have email addresses for "" go to my mailer server "".  However when I attempt to create the MX record on my DNS hosting provider, I receive a vague error message.

After digging about, I found the reason.  Apparently this configuration is "discouraged" because some mail systems may use the CNAME record to deliver mail instead of the correct MX record.  Some blame this on an ambiguous RFC definition.  While you CAN do this if you run your own BIND server, I could not do this within the limitation of my DNS provider.  So, I either have to change the email subdomain used or change the subdomain of the website.  Neither solution is pleasing to the eye in this scenario.  *sigh*