[Gormo]

Many email services offer disposable addresses integrated with your real email account.

Yahoo in particular has an excellent system for doing this; you can generate disposable addresses by adding a unique string to a base name particular to your account (but which isn't identical to your real address, as it is if you use a '+' delimiter with Gmail). By default, all messages received at any disposable address go to your primary inbox, but you can designate an alternate folder for each of them. Since all of your disposable addresses are @yahoo.com, it's impossible for admins to blacklist the domain.

Sorry if this sounds like a commercial for Yahoo Mail; I'm just very happy with this feature and almost never resort to using Mailinator et al.