Jeff, this is really interesting. Thanks for sharing. This answers a lingering question for me as far as what practical applications there can be for ARC in a context other than a mailing list.
Am I getting this right -- the way this would work is that another email platform would sign/"seal" a current state of the message authentication into the ARC header and then Microsoft, if it trusts that ARC signer, reads the ARC results to pass messages that would have perhaps otherwise failed authentication checks due to forwarding etc. past that point? Regards, Al Iverson On Thu, Jun 16, 2022 at 10:05 AM Jeff Dellapina via mailop < [email protected]> wrote: > Folks, > > > > As email passes thru our network, we make changes to the message. We may > add items to the header/footer or change links into “protected mode”. > Doing so breaks Authentication. > > > > Authenticated Received Chain (ARC). ARC helps preserve authentication > results *across* intermediaries. > > > > Learn more about ARC and how we make it work here: > > Improving “Defense in Depth” with Trusted ARC Sealers for Microsoft > Defender for Office 365 - Microsoft Tech Community > <https://techcommunity.microsoft.com/t5/microsoft-defender-for-office/improving-defense-in-depth-with-trusted-arc-sealers-for/ba-p/3440707> > > > > > > We have used ARC for a while, but this is the first time we rolled it out > to our 0365 customers. That said… there are some email filtering vendors > that are not using ARC which breaks authentication. In those cases, we are > forced to bulk or reject legitimate email sometimes from our own customers > who use email filtering services. > > > > > > Thanks, > > Jeff Dellapina > > > > Sr. Email Delivery Manager > > SAGE Team > > > _______________________________________________ > mailop mailing list > [email protected] > https://list.mailop.org/listinfo/mailop > -- Al Iverson / Deliverability blogging at www.spamresource.com Subscribe to the weekly newsletter at wombatmail.com/sr.cgi DNS Tools at xnnd.com / (312) 725-0130 / Chicago (Central Time)
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