> What MTAs do not honor this? sorry, i don't know what's sending when this happens
> How does 550 after DATA result in backscatter? perhaps because domain is 'old' spammers sometimes spam from $random@ those messages hit various providers which do *not* check dmarc, but then forward (either as a forwarding service or an internal system) to places that do check dmarc that causes bounces to be generated inside their systems which come back to me sometimes i go for days without seeing them, sometimes i get 100s an hour now i added code to detect this at the smtp level and 5xx respond > Not returning a 250 OK after DATA is still well within limits of the > SMTP dialog. How else are you supposed to reject a mail that could > be saved because of its size or because it has a virus? most software is pretty terrible more frequent of a problem are things that don't retry on a 4xx from greylisting _______________________________________________ mailop mailing list mailop@mailop.org https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
