It's convenient sometimes that sending email is free, but remember the fascinating read about the gmail anti-spam measures, and how they require central knowled

It's convenient sometimes that sending email is free, but remember the fascinating read about the gmail anti-spam measures, and how they require central knowledge? I'd bet you can satisfy 99.9% of my antispam needs with 2 rules: 1 - if I've ever sent an email to your address and haven't blacklisted you, you get to my inbox 2 - everyone else, pay 2-3 cents Note that mailing lists, via an email opt-in, would pass under rule 1. As for everyone else, if emailing addresses that have never conversed with you isn't worth a couple pennies, rethink sending the email.