It appears that Jaroslaw Rafa via mailop <r...@rafa.eu.org> said: >Dnia 20.01.2023 o godz. 08:46:24 Sebastian Nielsen via mailop pisze: > >> For example, replacing Date: with a Date: >> header containing server time, isn't wrong.Deleting characters from the >> subject which isn't part of codepage and creates garbled text in MUAs >> (or even outright crash MUAs) are also okay. > >As long as these headers are not DKIM signed. That's probably the main >reason in the advice "MTA should not mess with headers".
Good guess, but wrong. The distinction between submission and mail relay is much older than DKIM. A submission agent gets to clean up whatever crud it can, but once a message is being relayed via SMTP, the only changes should be trace headers at the top. (There used to be arguments about downcoding from 8bit to 7bit MIME, but it's been a decade since there have been any MTAs that don't handle 8bit.) Your MTA should either accept the message or reject it. I dunno about you, but MTA only looks at the headers enough to compute the DKIM signature and find the From: header for DMARC, and does not try to second guess senders about what else they might have meant to say. R's, John _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
