Gmail & Yahoo sender requirements

Since early 2024, Gmail and Yahoo enforce a common set of rules for anyone sending meaningful volume to their users (Gmail draws its bulk-sender line at roughly 5,000 messages a day to Gmail addresses, but the rules are best practice at any volume). Mail that doesn't comply is filtered to spam or rejected outright. These are requirements rather than suggestions. The good news is that each one maps to a step you have likely already taken.

Bulk senders must authenticate with SPF and DKIM, and publish a DMARC record. The authentication must also align, meaning it passes in the name of the same domain your recipients see in the From address.

What to do: verifying your sending domain covers all of it. Publishing the DNS records from your domain's detail page gives you DKIM signing in your domain's name and a DMARC record, and the return-path CNAME provides SPF alignment. SPF is evaluated against your bounce domain, which the CNAME points at us, so it passes and aligns without you adding an SPF record at your domain's apex. That is why you are never asked for an apex SPF entry. The walkthrough is in the sending domains guide. Once you've sent a test message, confirm it delivered in the email log; if you want to see the SPF, DKIM, and DMARC verdicts the receiving mailbox recorded, paste the received copy's raw source into the Email header analyzer. If you haven't published a DMARC record yet, the DMARC policy generator builds a valid one for you.

Marketing and promotional mail must carry a one-click unsubscribe option in the message headers (the technical standard is RFC 8058), which is the "Unsubscribe" link mail clients show next to the sender name. Opt-outs must be honored within two days.

What happens for you: the required one-click List-Unsubscribe headers are added automatically on marketing mail, which is now the default category, so any broadcast or marketing API send carries them, and recipients who use them are suppressed from future marketing mail immediately. A visible unsubscribe link is also added to the HTML of marketing sends, because the header button alone doesn't satisfy the visible opt-out recipients look for, and the ones who can't find a way out click "mark as spam" instead.

Senders must keep their spam-complaint rate below 0.3%, and ideally below 0.1%. This is the requirement that demands ongoing attention rather than one-time setup: 0.3% is roughly one complaint per 300 delivered messages, and providers filter aggressively once you cross it.

Where to look: the Metrics page in the dashboard tracks your complaint rate over time, and anyone who complains is suppressed automatically, so they are never mailed again. Staying under the line is about list quality: send to people who opted in, and prune the unengaged. See sender reputation monitoring for the thresholds and what to do when the rate climbs, and the email consent article for getting permission right in the first place.

Beyond these three headline rules, the providers' guidelines also expect basics that are handled for you as a matter of course, such as valid forward and reverse DNS on sending IPs and standards-compliant message formatting. Domain verification plus a clean list is genuinely the whole job.