[cracki]

this is backwards. advertisers WILL pay you money for your eye balls. legitimate senders will not because it's insulting to ask them for money. this is like dating vs prostitution. if you rate what to let near your eye balls by the highest bidder, you'll get all kinds of diseases.

[sparkie]

Advertisers will still pay, but they would need to adjust their strategy to target their ads more carefully to those who are likely to result in sales.

For legitimate senders, the attached fee would end up being spent by the receiver to send a reply, like a "refund", so it ends up zero-sum.

But for spammers it becomes an expensive option. Nobody is going to reply to the spam to "refund" their fee.