Peter Shute writes: > When MS365 forwards the mails sent to the distribution list, should > that make the DMARC authentication fail? I thought that only > happened if you made changes like adding a prefix to the subject > line like Mailman does.
If it forwards verbatim *and* the sending domain signs the mail with DKIM (the common case), DMARC validation will succeed. Without DKIM, DMARC validation is guaranteed to fail. However, even in the sender uses DKIM, *any* change *whatsoever* to the body will cause validation to fail, and there are several changes to the header that could cause it to fail. Furthermore, which parts of the header are protected by the DKIM signature are determined by the sender, not by DMARC AFAIK. If distribution lists are pure forwards, MS365 will be OK. But I find it hard to believe that that level of functionality is popular with users -- there's a reason why all popular MLMs implement subject prefixes, body headers and body footers, and it isn't "because it's the Microsoft way". ------------------------------------------------------ Mailman-Users mailing list Mailman-Users@python.org https://mail.python.org/mailman/listinfo/mailman-users Mailman FAQ: http://wiki.list.org/x/AgA3 Security Policy: http://wiki.list.org/x/QIA9 Searchable Archives: http://www.mail-archive.com/mailman-users%40python.org/ Unsubscribe: https://mail.python.org/mailman/options/mailman-users/archive%40jab.org