Post by e***@businessconnect.nlPost by Burkhard OttHi,
We'r running postfix as relay server for broadbandcustomers. Since
this server has no local recipients; we cannot check for the
existence of the recipient before accepting the message.
This leads to undeliverable's and backscatter spam.
How do we need to setup our postfix to prevent this ?
Regards,
Eddy Mouws
http://www.postfix.org/BACKSCATTER_README.html
Hi Burkhard,
That link doesn't provide the information we need; it's based on running
postfix as destination; not as relay-server.
Regards,
You can only filter on certain things like the headers, which can reduce
backscatter dramatically, however a few will come through.
The other question is are you allowed to filter on a path though system?
To put it into perspective, as a transport relay, your job is it to
transmit email, regardless of it's content. The final destination
(client) has to make the decission if it wants the email or not, you
can't think for them. You can set a header flag for the client if you
want, but if you entirely filter something out will lead to complains and
more hassles, especially if the client (destination) doesn't know about
filter actions.
If I would be your customer and would find out, well I would move on,
carriers are supposed to carry bits, not taking care of my business.
If a client agrees on such action (he pays full price for half the
internet in that case), you could filter the domain and check what the
supposed MX record, that however will lead to a problem when the sender
is valid (a customer using his email addres via a different MX or tries
to send directly).
In my opinion, only on the target systems is would make sense to filter.
cheers