Disposable email addresses

SpamGourmet looks a useful utility to generate disposable email addresses and I've started using it.
One problem, though, is that each address has a maximum of 20 "sends" so that the twenty-first email from whoever you gave that address to won't be received by you. Could be that a company that you weren't sure about, actually turns out to be useful to you but now the email you gave them will become useless.