email domain change to cname if the domain is DNS aliases

Please help on my case :
We send email to test@billionelite.cn but pmg change the email address to test@g1-excn.ssl.cdncenter.cn
since the change it resolve an invalid MX record and the email cannot be sent.
This problem is applied to all similar cases if the email domain is a DNS aliases.

Condition :
billionelite.cn -- a DNS aliases
g1-excn.ssl.cdncenter.cn -- a DNS cname

How to enforce pmg not to resolve and use cname?

Thanks!