I think it would be better to make all communications require an acceptance. Like accepting a facebook friend, of google hangouts. Then charge for acceptances

I think it would be better to make all communications require an acceptance. Like accepting a facebook friend, of google hangouts. Then charge for acceptances, even $0.10 per user would likely be not a big deal for users, but prohibitive for spammers who want to message millions and only a very small fraction will be gullible enough to pay for whatever the spammer is selling.