Restricting email


I want to set up an email filter so an account can only accept email fom one of two addresses. But the stardard filtering page seems only to allow ANDing of rules
I want to say:
if envelope-from contains foobar accept
if envelope-from contains zarniwoop accept
otherwise discard

I’m guessing I have to set up a .procmailrc file to do this. But that raises another questions. Where would I put such a file?