It's important to say to the impatient among us that the first alpha release is not due earlier than the end of June,
Actually, the release schedule page has the first alpha release on June 3. The second alpha is end of June (actually July 1st.)
I don't see why mailing lists are an issue with a micro-payments system. There would be no need to attach a payment to mailing list emails (or to emails with friends/family, etc) since supposedly you would just add that address to your address book and they would be allowed through. After all *you* subscribed to the mailing list, so you are expecting emails from them.
It seems you would only need to attach a payment to an email if the recipient doesn't know you (and so wouldn't have you in their address book) or if it is urgent enough that you want to make *sure* it gets read.
If at first you don't succeed, you are running about average.