Gmail and Yahoo sender requirements explained

What the requirements are

Since February 2024, Gmail and Yahoo require everyone who sends them email to authenticate it, and bulk senders to meet stricter rules: SPF and DKIM, a DMARC record, one-click unsubscribe and a low spam complaint rate. Mail that does not comply gets deferred or rejected, typically with bounces like 550 5.7.26 or 421 4.7.28. Google defines a bulk sender as one that has sent close to 5,000 or more messages to Gmail addresses in a day; once a domain qualifies, it is treated as one from then on.

All senders

Requirement	Details
SPF or DKIM	At least one must pass for the sending domain
Reverse DNS	The sending IP has a PTR record that resolves back to it
TLS	Connections to the receiver use TLS
Spam rate	Below 0.3% as reported in Postmaster Tools (aim for under 0.1%)
Message format	Valid headers per RFC 5322; no impersonating Gmail addresses in From

Bulk senders, additionally

Requirement	Details
SPF and DKIM	Both set up for the sending domain
DMARC	A record on the From domain, at least `p=none`
Alignment	The From domain matches the SPF or DKIM domain (DMARC alignment)
One-click unsubscribe	`List-Unsubscribe` and `List-Unsubscribe-Post` headers (RFC 8058) on marketing mail, honored within two days
Spam rate	Stays below 0.3%

Transactional mail such as password resets and receipts does not need the unsubscribe headers. Yahoo's published rules match Gmail's on the main points; small differences in wording and thresholds exist, so check each provider's current sender guide if you are close to a limit.

Enforcement was phased in during 2024, starting with temporary errors on a share of non-compliant traffic and moving to rejections. Google has said it continues to tighten enforcement, so a domain that got away with gaps before may start seeing bounces. Microsoft added similar rules for Outlook.com in 2025, rejected with 550 5.7.515.

Records that meet the rules

example.com.                IN TXT "v=spf1 include:_spf.google.com include:mail.example.net -all"
s1._domainkey.example.com.  IN TXT "v=DKIM1; k=rsa; p=MIIBIjANBgkq..."
_dmarc.example.com.         IN TXT "v=DMARC1; p=none; rua=mailto:dmarc@example.com"

The headers for one-click unsubscribe on a marketing message:

List-Unsubscribe: <https://example.com/unsubscribe?u=8f3a2c>, <mailto:unsubscribe@example.com>
List-Unsubscribe-Post: List-Unsubscribe=One-Click

The HTTPS URL must accept a POST with the body List-Unsubscribe=One-Click and unsubscribe the recipient without asking them to log in or confirm. The message must be DKIM-signed with these headers included in the signature.

How to check you comply

Check the DNS records for SPF, DKIM and DMARC on your From domain.
Send a test to a Gmail address and open "Show original". Look for spf=pass, dkim=pass and dmarc=pass in Authentication-Results, or paste the headers into the Email Header Analyzer.
Check reverse DNS of your sending IP if you run your own server: dig -x 203.0.113.25 +short.
Watch your spam rate in Google Postmaster Tools, which needs the domain verified in DNS.
Check every service that sends as your domain (newsletter tool, CRM, billing system), not just your main mailbox.

DMARC p=none: the minimum policy, and how to move beyond it.
SPF too many DNS lookups: a common reason SPF quietly fails.
DKIM none: mail that arrives with no signature.
550 5.7.26: the bounce for unauthenticated mail.

Check your domain against the authentication rules with the Email Checker.