No Alias option available for maildomains..

Hi,
 
This is a feature that should be include with HC (And I don't understand why it's not already there).
We should have the option to used a parked domain and add this domain as a e-mail allias.
 
EX :
In my "mydomain.com", I've parked "example.com".
I should have the option to created a alias "example.com" to the mail domain "mydomain.com".
 
The equivalent of domain foward in cPanel, and this is already the case in Plesk and was the case in Helm.
 
In the case of HC, I would see this Mail Domain Menu (Acould add a Property option and be able to place a parked domain as a alias).
 
Thank you!