Selective mangling of from address enabled because of DMARC issues

Hi, As you may or may not be aware, it is becoming increasingly popular for large email providers to use DMARC settings with failure policies of "quarantine" or even "reject". Domain-based Message Authentication, Reporting and Conformance (DMARC) is a mechanism which builds upon SPF and DKIM to try to ensure that emails that show a given domain name in the From: address came from mail relays which are able to sign headers to prove they can send such emails. As Mailman takes your posts and modifies them (the subject line is altered and list footers may be added) yet retains your specified From address, this causes a DMARC failure and for receiving sites is indistinguishable from a forged email. There are people posting to these lists right now from domains which have strict DMARC failure policies. As a result whenever they post to the BitFolk lists, many recipient sites do as instructed and reject or quarantine their email. Furthermore a rejection causes the list software to consider the *recipient* as having bounced the email, and if this happens several days in a row the recipient address will be considered undeliverable and will be automatically unsubscribed. In short, posters whose domains have strict DMARC failure policies can cause other subscribers to be unsubscribed from the list. There is no good way to avoid this for typical mailing lists. I've decided that one of the least bad ways is to enable the setting that rewrites the sender from address (only) for domains which have strict DMARC failure policies. So, if you see something like: From: Joanne Bloggs via users <users(a)lists.bitfolk.com> instead of the more usual: From: Joanne Bloggs <jbloggs(a)example.com> then this is the reason why. The purpose is to have the messages that we know will break DMARC come instead from the lists.bitfolk.com domain. Cheers, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting