Il 19/05/2014 23:26, Angus McIntyre ha scritto:
Tonix - Antonio Nati wrote:
About deleting all email for not existing users, I consider it a bad
service to customers, as they have legitimate raports with business
partners, and if someone writes to the wrong address it is correct and
ethical to report them back that address is wrong, so they can use
another way to contact the recipient, instead of waiting for never
coming reply messages.
I take your point, but the volume of attempted deliveries to non-existent
addresses is increasing continuously. Some of the domains I manage each
receive messages daily sent to literally hundreds if not thousands of
addresses that do not exist and have never existed.
Sometimes the bogus addresses are clearly the result of bad de-munging by
spamlist generators. For example, if you have a real address
'system-reports@', the spammer might try to send to 'reports@', having
mistakenly stripped off the first part. I've also seen attempts to deliver
to what were obviously once message IDs that have somehow been scraped up
by spammers and added to a list under the impression that they were email
addresses. Then there are the spammers who permute real addresses (i.e. if
you have someuser@, they might create a fake sender address of
'xyzsomeuser@') and these get fed back into the address collectors as
well. And some just seem to be invented by combining random characters.
If you bounce all these, then you will generate huge amounts of email,
much of it going back to real users whose addresses have been forged in
the 'From' line of the spam message.
Reject at SMTP level is the best practise, no traffic involved, and the
email remain in charge of the sending server.
SPF should help avoiding emails to real recipients from forged senders.
More, the abuse of deletion and missing respect for RFC forces users to
ask always for delivery and read receipt, incrementing the volume of
useless emails.
I don't like read receipts, but I think the volume of worthless mail
generated is a fraction of what you'd get if you bounce every message to a
non-existent user.
Again, why do you bounce it instead of stopping it at SMTP level?
Regards,
Tonino
Of course, I have to admit that the spammers who are targeting these
nonsense addresses are more likely than others to be rejected at
connection time by spamdyke's RDNS checks or SaneSecurity, so maybe the
bounce volume would be smaller than I expect. Still, the potential is
there.
Angus
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