Stop Delivery Failure bounces to Postmaster
gom...@gmail.com
I have recently been inundated with what looks like legitimate email,
however the incoming addresses are slightly modified such as adding a
number or letter or both to the address which of course then bounces.
It started on Easter monday and is continuing currently. I have anti-
spam measures in place but it does not pick it up. In order to reduce
my administrative issue of having to delete the hundreds of messages
each day it was suggested to turn off delivery of Undeliverable
messages(or copies at least) to the Postmaster account.
How is this done in Sendmail 8.13.1? I realize I could also create a
rule in my mail client to send to the trash any messages from
Postmaster or that have Delivery Failure in the subject line as well,
but thought I would at least make an attempt at correcting at the mail
server rather than it actually even being sent.
Thanks in advance,
John
Tilman Schmidt
> I have recently been inundated with what looks like legitimate email,
> however the incoming addresses are slightly modified such as adding a
> number or letter or both to the address which of course then bounces.
Not "of course". It shouldn't bounce. It should be rejected immediately
during the SMTP session.
> In order to reduce
> my administrative issue of having to delete the hundreds of messages
> each day it was suggested to turn off delivery of Undeliverable
> messages(or copies at least) to the Postmaster account.
That is of course possible (just set the confCOPY_ERRORS_TO variable to
an empty value in your sendmail.mc file) but a much better solution
would be to avoid generating those bounce messages in the first place.
For one thing, even if you don't send them to the Postmaster account,
you will still send them out to the forged sender addresses, which is
called backscatter and is the whole point of the exercise from the
spammer's point of view. So you'll be helping the spammer and risk
ending up on blacklists.
HTH
T.
--
Please excuse my bad English/German/French/Greek/Cantonese/Klingon/...
JF
> gome...@gmail.com schrieb:
I would rather stop this backscatter altogether and have the messages
end. If I can explain my mail routing as we use a third party for
inbound/outbound email.
Diagram(sort of):
<Email from Internet>
to
<Mail Transport System(MTS), 3rd party>
to
<SPAM & AV Checking, 3rd party>
to
<Sendmail>
<if mailing list address then dealt with, otherwise sent to
smarthost/relay internally>
to
<Exchange 2007, for some domains>
or
<Domino 7.x, for remaining domains>
What usually happens is that a message(SPAM) gets caught between
Exchange/Domino & Sendmail for the 25 bounces. All clients mail
however is retrieved from Exchange, as our conversion from Domino to
Exchange is not quite finished which is the reason the mail routing is
as it is currently, but not forever.
I am looking at using a LDAP Routing feature in sendmail which may
work for me as the LDAP server would look up into my AD to check on a
user, the only issue of course is anyone sending to one of the few
majordomo lists that are running.
If anyone can assist or has some tips on stopping the backscatter
would be appreciated as I am by no means a sendmail guru or even a
*nix guru being in a small organisation doesn't allow that level of
specialisation.
Thanks again,
John
Per Hedeland
<b318be10-4870-4858...@a32g2000prf.googlegroups.com> JF
<gom...@gmail.com> writes:
>
>I would rather stop this backscatter altogether and have the messages
>end. If I can explain my mail routing as we use a third party for
>inbound/outbound email.
>
>Diagram(sort of):
>
><Email from Internet>
>to
><Mail Transport System(MTS), 3rd party>
>to
><SPAM & AV Checking, 3rd party>
>to
><Sendmail>
> <if mailing list address then dealt with, otherwise sent to
>smarthost/relay internally>
>to
><Exchange 2007, for some domains>
>or
><Domino 7.x, for remaining domains>
Doing anything with sendmail to prevent backscatter in this setup is way
too late - rejection of invalid recipients (etc) must happen at "Mail
Transport System(MTS)". If you reject with sendmail, you will just force
"SPAM & AV Checking" to send the bounce - no improvement as far as
backscatter is concerned. Likewise if "SPAM & AV Checking" rejects spam
& V, it will force "Mail Transport System(MTS)" to send a bounce.
--Per Hedeland
p...@hedeland.org