Gmail and Yahoo sender requirements for B2B outbound: SPF, DKIM, DMARC and the 0.3% spam line
Since February 2024, Gmail and Yahoo publish hard requirements for anyone sending to their users. Miss them and mail is rate-limited, sent to spam or rejected, no matter how good the copy is.
Requirements for every sender
Both providers list the same core rules for all senders:
- Authenticate with SPF or DKIM at minimum.
- Valid forward and reverse DNS (a PTR record) for sending IPs.
- Keep spam complaints below 0.3%. Google recommends staying below 0.10% and never reaching 0.30%.
- Format messages to RFC 5322 (Yahoo also cites RFC 5321), and use TLS (Google).
Extra requirements for bulk senders
Google applies these to senders of more than 5,000 messages a day to Gmail accounts; Yahoo calls them its bulk-sender requirements:
- SPF and DKIM, plus a published DMARC record (a policy of
p=noneis acceptable). - Alignment: the From: domain must align with the SPF or DKIM domain so DMARC passes.
- One-click unsubscribe (List-Unsubscribe and List-Unsubscribe-Post headers, RFC 8058) for marketing and subscribed messages, plus a visible unsubscribe link in the body. Yahoo asks that unsubscribes be honored within 2 days.
What this means for a small outbound program
- Authenticate fully even if you're small. SPF, DKIM and DMARC cost nothing and Google recommends them for every domain.
- Use separate sending domains or subdomains so your main domain's reputation isn't tied to outbound. Yahoo recommends segregating mail types by IP or DKIM domain.
- Ramp slowly. Google advises starting with low volume and increasing gradually, avoiding sudden spikes.
- Honor opt-outs fast. CAN-SPAM allows 10 business days; Yahoo asks for 2. Use the shorter one.
- Watch complaint rates in Google Postmaster Tools and Yahoo's Complaint Feedback Loop.
- Write honest headers. Google's guidelines name fake "Re:"/"Fwd:" subjects and misleading display names as practices to avoid.
Quick DNS checklist
| Record | Purpose |
|---|---|
| SPF (TXT) | Lists the servers allowed to send for the domain |
| DKIM (TXT or CNAME) | Signs each message; Google requires keys of 1024 bits or more and recommends 2048 |
| DMARC (TXT at _dmarc) | Tells receivers what to do when checks fail; add a rua address for reports |
| PTR | Reverse DNS for the sending IP; usually handled by your mailbox provider |
The legal side is separate: see our CAN-SPAM checklist for B2B cold email.
Written by AI agents for Reply Garden and checked against the sources below on October 27, 2026. General information, not legal advice. Spotted an error? Email hello@replygarden.com.
Sources
- Google: Email sender guidelines
- Yahoo Sender Hub: Sender requirements and recommendations
- RFC 8058: One-click unsubscribe
- Google Postmaster Tools
Rather have it run for you? Reply Garden runs compliant outbound email for small US B2B firms: licensed data, separate sending domains, copy you approve, and interested replies forwarded within a business hour. No promises about meetings or revenue.