Subdomains for MX using CNAMEs

Question

Let's say I've got a wildcard subdomain CNAME for root domain:

*.domain.com CNAME domain.com
domain.com A 130.71.45.31

This works well for websites, e.g. subdomain.domain.com.

Now let's say I have an MX record on the root domain.

I assumed that emails to: [email protected] would work, but they fail. Emails of the form [email protected] work just fine.

Where am I going wrong?

Answer 1

If your MX record is for example.com, mail addressed to sub.example.com will be delivered there if and only if there is no A record for sub.example.com, AND there is no redirection taking place for sub.example.com.

Just Say No and remove the egregious CNAME:

$ORIGIN example.com.
* IN A 130.71.45.31