Derek J. Balling wrote:
At the end of the day, though, there's an obligation to tell the
sender "this message with your address on it was undeliverable".
It's up to them to filter as they see fit. If it's truly as you
say, overwhelming, they can just as easily drop everything with FROM:<>
into the bit-bucket themselves, and lose the "5% that matter baby"
along with the bathwater.
But that's THEIR decision to make, and no one else's.
Strictly local policy, not to be used as a basis for protocol design
or breaking protocol.