Bulk sender requirements checklist
Gmail and Yahoo began enforcing sender requirements in February 2024. Outlook.com started on 5 May 2025 for domains sending more than 5,000 messages a day, first routing non-compliant mail to Junk and later rejecting it with 550 5.7.515.
| Requirement | Gmail | Yahoo | Outlook.com | Checkable in DNS? |
|---|---|---|---|---|
| SPF passes | yes | yes | yes | record validity and the 10-lookup limit: yes |
| DKIM passes | yes | yes | yes | key published at a selector: yes; signing: no |
| DMARC published (p=none or stricter) | yes | yes | yes | yes |
| SPF or DKIM aligned with From | yes | yes | yes | needs a real message header |
| One-click unsubscribe (RFC 8058) | yes | yes | recommended | no |
| Spam rate under 0.3% | yes | yes | - | no |
Run the DNS part of this checklist; the result includes a bulkSenderReadiness verdict.
Sources: Google email sender guidelines, Yahoo Sender Hub, Outlook.com postmaster policies, Microsoft 550 5.7.515.