Fastmail has that same technique, and it is very nice. I have run into sites where I sign up for an email where they do not allow the "+" (presumably to prevent you from doing a "[email protected]"). My only concern with this is it seems like with either way, it would be trivial for a spammer to figure out your real email address (i.e. [email protected], use a regular expression to convert it to [email protected]). How hard would it be to maybe alias [email protected] and [email protected] so they both go to [email protected]? or maybe [email protected] also aliases. That way it makes it that much harder to derive the original email address.