Forwarding and mailing lists are the largest source of legitimate DMARC failures. ARC lets receivers accept mail that would otherwise be quarantined under p=reject.
Mistake 1: Expecting ARC to fix your own outbound authentication; it only helps intermediaries#
Why it hurts: this undermines ARC (Authenticated Received Chain) at the point where mailbox providers make their decision, and it is rarely surfaced by your own tooling until placement drops.
Fix: Check whether your inbound gateway or mailing-list software supports ARC sealing.
Mistake 2: Trusting ARC from unknown sealers, which reopens the spoofing door#
Why it hurts: this undermines ARC (Authenticated Received Chain) at the point where mailbox providers make their decision, and it is rarely surfaced by your own tooling until placement drops.
Fix: Enable ARC sealing on any system that modifies and re-sends mail.
Frequently asked questions#
Do I need ARC as a sender?
No. ARC is implemented by intermediaries and receivers. Senders benefit indirectly when their mail is forwarded.
Which providers honor ARC?
Gmail, Microsoft, and Yahoo all evaluate ARC when deciding whether to override a DMARC failure.