Vasya Pupkin wrote:
Hello.
First, I have spent two days reading articles and searching web for
solution but failed there. I am using postfix as an mx for my domains,
it accpets mail for different addresses withing my domains which is
then forwarded to other external domains, i.e. google.com and other
mail services. Mail for unknown users is rejected, many other check
are performed, but still sometimes my system acts as a backscatterer
when something like this happens:
1. Incoming mail passes all tests, it's coming to one of the addresses
within my domain, i.e. existing-u...@mydomain.tld
2. Postfix then forwards mail to external domain, i.e. myem...@mailservice.tld
3. For some reason mailservice.tld rejects this mail, i.e. it doesn't
like it's content or size.
4. Postfix then bounces mail to sender, which can be forged, and thus,
becoming a backscatterer.
Is there any way to prevent postfix from sending bounces anywhere?
I am dealing with the same thing. I have to forward to non-local mail
servers and I try to mimic some of those settings but we still get a few
that pass local mail to external mail which is then rejected.
Maybe a script that checks for the rejects and discards would work? I
will think through that approach for use here actually.
RCR
Linux System Administrator
