Is there a way in Postfix to limit email relays to non-existent users?
For example, if an email has over 25% failures in its email sending
attemps in the last hour, block that email for an hour or so.
When, say, hacked scripts are used by spammers to send mass emails, this
would help limit the amount of damage.
I know recent cPanel versions have this sort of check that will reject
email relaying when a email domain exceeds, for example, more than 25%
relays to non-existent email users.
When that happens, the CPanel server outputs something like:
Domain has exceeded the max defe