[otrs] Customer users based on email domain

Hi all, I'd like to know if it's possible, and if so, how would I do the following: We're setting up OTRS for our internal use and to provide IT support to a few customers. All communication will be done via email, both creating and replying to tickets and therefore, we have no real need of customers accessing the customer portal. I would however like to associate each new user email with a customer id. So, users that create a ticket from me@acme.co are assigned to Acme Co. Users from me@evil.corp are assigned to Evil Copr. etc. Is this possible of to I have to manually create a customer user and associate it with a customer ID for Acme and Evil Corp.? Cheers, Pedro