Filtering Email

[Matthias Fechner]

Am 05.01.2017 um 09:12 schrieb Matthew Seaman:
> There's a potential problem with rejecting email from your local server
> -- backscatter.  If your upstream MTA has accepted a message for
> delivery and then your local MTA later decides to bounce it, there is no
> choice other than to send the bounce to the sender address in the mail
> headers, and spammers nowadays forge that address, so you end up
> resending the spam to some (possibly innocent) third party.  It's better
> to just /dev/null the messages in such circumstances.

hm, this is really dangerous, you could kill by this action real email
without notify the sender.
I would recommend that the sender set a SPF record to control which
server is allowed to use their domain.
This would mitigate this problem and forge of email headers is not
possible anymore.


Gruß
Matthias

-- 

"Programming today is a race between software engineers striving to
build bigger and better idiot-proof programs, and the universe trying to
produce bigger and better idiots. So far, the universe is winning." --
Rich Cook


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