On Aug 12, 2010, at 10:32 AM, John R Levine wrote:
Talking out of my hat here, it is my impression that spam is much more
likely to be sent to bogus addresses than legit mail is, so however the
spam fraction of your mailstream, the spam fraction of your bounces is
likely to be even higher.
Maybe. But I've seen some *really* effective anti-spam/anti-blowback
mechanisms catch that junk and throw it on the floor at the "original
side, while still allowing "legit" bounces to go through just fine (the
Ironport A/S stuff works really, really, well, the last time I used it).
That's been my experience as well.
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.
Yep. I'll also point out that since senders can track the messages they send,
they also have the option of correlating NDNs to those messages and throwing
out the ones that don't line up with anything.