Since February 2024, anyone sending more than 5,000 messages a day to Gmail or Yahoo must meet a shared checklist. Enforcement ramped through 2024 and is now routine: fail it and mail is rejected or filtered wholesale. The rules are worth meeting even far below 5,000/day — they are simply what a legitimate sender looks like.
Not either/or, as it used to be. Both must be published and passing. Watch the
10-lookup limit: an SPF record in
permerror counts as no SPF at all.
p=none is enough to satisfy the requirement. It is not enough to protect you
— see policy choice.
The From: domain must align with either the SPF domain or the DKIM d= domain.
Sending through a vendor on the vendor's own return-path fails this even though SPF passes.
Marketing and subscribed mail needs both headers, and the unsubscribe must take effect within two days:
List-Unsubscribe: <https://example.com/u/abc123>, <mailto:[email protected]> List-Unsubscribe-Post: List-Unsubscribe=One-Click
Measured in Google Postmaster Tools. Google advises staying under 0.1%; 0.3% is the hard ceiling. Above it, filtering hits everything you send, and recovery takes weeks.
Your sending IP needs a PTR record resolving back to a hostname that resolves to that IP, and connections must use TLS.
Almost everyone can publish a DMARC record. The failures cluster in alignment (vendor mail that passes SPF for the wrong domain) and spam rate (a purchased or stale list). Neither is fixed by a DNS edit alone.
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