Entirely possible - but here's something cool. I have Google for Your Domain setup for a personal domain. I just tested it, and I was able to send an email to: jon+test@[mydomain].com. Now there's no way for a spammer to know if Google is handling my mail (easily) so they'd have to assume that the + was a legitimate character. I mean, in theory, they could lookup the MX records and if they point to google, strip the +[characters up to]@ off, but I seriously doubt many, if any at all, would do this.