[Dovecot] virtual user login

[Paul A]

Hi, 

I have server with multiple virtual domains and this server also accepts
mail for the local domain.

I'm using postfix and have the following setup for a virtual

sales at domain.com mapped to custsales at localhost

I was wondering if there is a way to login with the virtual email address,
for example sales at domain.com?

I would also like to still be able to login with the local user as well. 

TIA, P