Forwarding breaks SPF because the forwarding server isn’t in your SPF record, so the check fails at the final destination. DKIM survives forwarding (the signature travels with the message, if content isn’t altered), which is why a DMARC setup that relies on aligned DKIM stays reliable where SPF alone would fail.
SPF authorizes the server that connects to the recipient. When mail is forwarded, that server is the forwarder — not you — so SPF fails. DKIM signs the message itself, so as long as a mailing list or gateway doesn’t rewrite the body, the signature still verifies after forwarding.
Make sure DKIM is enabled and aligned to your domain on every sending service — that gives DMARC a path that forwarding doesn’t break. For mailing lists that modify messages, ARC (Authenticated Received Chain) helps receivers honor the original authentication.
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Open the free DMARC checker →No — SPF still matters and is required, but you shouldn’t rely on it alone for DMARC. DKIM alignment is what makes DMARC robust against forwarding.
