we have a problem when using mx and cname records. The reason we are using a cname record is that our virtual machines are hosted on Windows Azure and so they've dynamic ips.
We have the following setup:
customer.tld -> (CNAME) -> host.our-hosting-domain.tld -> (A/MX) Windows Azure
The reason we are using A/MX records at our configuration even if Azure has dynamic ips is that we need an mx record for incoming emails. These A/MX records are updated by a script on the server every 60 minutes.
The problem is the following: if i send an email to firstname.lastname@example.org it automatically changes the recipient address to email@example.com which is obviously the CNAME record.
An alternative would be of course to point the A/MX records directly from the domain to azure by using A/MX-Records, but then we would have to register all customer domains on our own (because we need the login credentials of the domain registry for our script).
Is there any way to prevent this? Or is this by CNAME-design?