Login to webmail with alias email address instead

[ideance]

Hello,

I have a main domain name and a few aliases. Assigned with the main domain name I have some email addresses. Now the main website is one of the aliases. That wouldn't be such a problem if I wouldn't need to have users to be able to login to webmail by using the entire email address.

So my question is: is there any way to allow users to login to webmail using full alias email address?

Example:
email@maindomain.com
email@aliasdomain.com

Login to webmail with email@aliasdomain.com instead of email@maindomain.com

Thanks!