Setting mail filters with fetchmail

I am using fetchmail to pull mails for RT (4.4.2), I wanted to set a filter to drop all mail from everywhere except one domain. Could that be done with fetchmail? My mail server is remote , I do not have access to it. I was given a username/password to connect to the mail box to pull e-mails from it. I just don’t want everyone creating a ticket except users from one particular domain (with their e-mail addresses…).

If that the above is not possible, then is there way to accomplish this within RT?