Google, Yahoo and Microsoft Enforce Bulk Email Sender Rules

On Feb. 1, 2024, Google and Yahoo began enforcing new requirements for bulk email senders defined as those sending more than 5,000 messages to Gmail addresses in one day, according to MarTech.

Authentication requirements

All three providers require bulk senders to implement SPF to identify authorized email servers, DKIM to add digital signatures verifying authorized senders, and DMARC to specify actions on authentication failures and enable reporting. The story was updated to include DMARC upgrades along with new deliverability analysis in Google Postmaster Tools.

Spam rate thresholds

Google requires bulk senders to keep reported spam rates below 0.10 percent in Google Postmaster Tools and avoid reaching 0.30 percent or higher. Non-compliant traffic initially receives temporary errors with error codes. Email rejections began in April 2024, with Google stating it would start rejecting a percentage of non-compliant traffic and gradually increase the rejection rate.

Unsubscribe functions

Bulk senders must support one-click unsubscribe for marketing and subscribed messages. The requirements also cover reported spam rates and the ability to easily unsubscribe from email lists.

Microsoft restrictions

In April 2025 Microsoft announced restrictions on high-volume senders sending 5,000 emails or more to Outlook.com domains that mirror the Google and Yahoo rules. Microsoft originally planned to route non-compliant messages to the Junk folder on May 5, 2025, but later changed the action to outright rejection starting on that date, according to MarTech.