Rules for every sender#
Gmail and Yahoo set a baseline for anyone sending to their users, whatever the volume. Low-volume cold email from a normal business mailbox has to meet these too.
| Requirement | Gmail | Yahoo |
|---|---|---|
| Authentication | SPF or DKIM | SPF or DKIM |
| Spam rate | Below 0.3% in Postmaster Tools | Below 0.3% |
| Forward and reverse DNS (PTR) | Required | Required |
| Message format | RFC 5322 | RFCs 5321 and 5322 |
| Other | TLS for transmission; don't impersonate Gmail From: headers | — |
From the providers' published requirements, checked 18 October 2026.
Extra rules for bulk senders#
Gmail defines a bulk sender as one that sends close to 5,000 messages or more to personal Gmail accounts within 24 hours, counting everything sent from the same primary domain. Once classified, the status doesn't expire. Yahoo doesn't publish a threshold.
- SPF and DKIM both set up
- DMARC published, at least p=none
- The From: domain aligned with the SPF or DKIM domain
- One-click unsubscribe (List-Unsubscribe header, RFC 8058) on marketing messages
- A clearly visible unsubscribe link in the body
- Unsubscribes honoured within 2 days (Yahoo) or within 48 hours (Gmail's recommendation)
Outlook.com#
Microsoft announced in 2025 that domains sending more than 5,000 emails a day to its consumer addresses (outlook.com, hotmail.com and live.com) must pass SPF, DKIM and DMARC. From 5 May 2025 non-compliant messages were routed to Junk, with rejection possible later.
What it means for cold email#
Most cold outreach to businesses goes to company domains hosted on Google Workspace or Microsoft 365, not to personal Gmail or Outlook.com accounts. Gmail says its sender requirements apply only to personal Gmail accounts. That doesn't make them irrelevant: company mail filters look at the same signals, and many small businesses do use a personal Gmail or Outlook.com address.
The practical consequences are the same either way. Authenticate your domain, keep volume low per mailbox, give every email a working opt-out and watch complaints. One complaint in a few hundred cold emails already pushes you towards the 0.3% line.
How to check where you stand#
- Send a test email to a Gmail address and choose “Show original”: SPF, DKIM and DMARC should say PASS.
- Verify your domain in Google Postmaster Tools and look at the spam rate and compliance status.
- Check that your DMARC record exists and that the From: domain matches the signing domain.
- If you send marketing at volume, confirm the List-Unsubscribe headers are present and that unsubscribes are processed within two days.
FAQ
What are Gmail's bulk sender requirements?
Senders of close to 5,000 or more messages a day to personal Gmail accounts need SPF, DKIM and DMARC (at least p=none), alignment, one-click unsubscribe on marketing messages, valid forward and reverse DNS, TLS and a spam rate below 0.3%.
Do Gmail's sender rules apply to cold email?
The rules for all senders apply to every email sent to a personal Gmail account, including cold email. The bulk rules apply once you send close to 5,000 a day to Gmail accounts from one primary domain.
Do the Gmail rules apply to Google Workspace recipients?
No. Google says the sender guidelines apply only to messages sent to personal Gmail accounts. Workspace customers have their own filtering, which looks at similar signals.
Does Yahoo have a bulk sender threshold?
No. Yahoo says it classifies bulk senders by significant volume but doesn't specify a number.
Do I need one-click unsubscribe for one-to-one sales emails?
Gmail requires it for marketing and promotional messages from bulk senders. For low-volume cold email, a clear opt-out line or link in every email is still expected, and it lowers complaints.
Sources
- Email sender guidelines · Google
- Email sender guidelines FAQ · Google
- Sender Requirements & Recommendations · Yahoo
- Sender FAQs · Yahoo
- Strengthening Email Ecosystem: Outlook's New Requirements for High-Volume Senders · Microsoft
- RFC 8058: Signaling One-Click Functionality for List Email Headers · RFC Editor