On Mon, Oct 30, 2023 at 02:36:33PM +0100, Szymon Malinowski via Postfix-users <postfix-users@postfix.org> wrote:
> Hello > > We've just launched postfix with Mailscanner and spamassasin on our mail > server. > > Everything is working great, but we've encountered very funny and strange > problem. > > We've recieved an email which was classified as spamm by it's sender IP > address by RBL list. > > Additionally sender address didn't pass DMARC verification and had RUF email > in it's DNS record. > > Our mail system based on DMARC DNS record send a DMARC report to that email. > > However email in that record was invalid, and the destination server bounced > it with reason that the user is unknown. > > This bounced email was sent to us and was also classified as SPAM and was > rejected + again didn't pass DMARC verification which resulted in another > email with report to the invalid email adress which is in RUF DNS record. > > You see the point? We got stuck in a loop of sending DMARC reports which are > beeing bounced because of unknown user. > > Is there any way to prevent such situations? > > Right now we simply blocked that IP address on mail server firewall but this > could happen any time again in the future. > > Anyone every encountered this kind of situation? I've had this happen with one domain. I ended up with megabytes of bounce messages. You can try reporting the problem to the domain with the bad records, but if that fails to fix the problem, you need to stop sending report emails (or arrange to send that domain's DMARC reports to /dev/null or similar). And then submit a bug report for whatever software is sending the DMARC report. If the bug is fixed, you can turn reporting back on. cheers, raf _______________________________________________ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
