Uh, email servers already prevent people who are not part of the domain from sending email. Most of them anyway. There's not too many open relays, I think they're called, anymore.
And I don't see how requiring the user to enter a catchpa every day would really prevent any spam if they only have to enter it once and they're on that domain legitimately.
Maybe if every email they had to enter a different catchpa it would do something... except for the fact that they've cracked every one out there already, so it really wouldn't.
And I don't see how requiring the user to enter a catchpa every day would really prevent any spam if they only have to enter it once and they're on that domain legitimately.
Maybe if every email they had to enter a different catchpa it would do something... except for the fact that they've cracked every one out there already, so it really wouldn't.