Gmail, Yahoo & Outlook Sender Requirements Checker
Gmail, Yahoo and Outlook.com now reject mail from senders that don’t authenticate it. Enter your sending domain and see whether SPF, DKIM and DMARC meet the requirements - and which of the other rules you still have to verify yourself.
What the providers require
- SPF or DKIM must pass for every message. Mail with neither is rejected, with errors like 5.7.26 at Gmail.
- A sending IP needs working reverse DNS, and the connection should use TLS.
- Keep the spam complaint rate low - 0.1% is the safe target, 0.3% the line you must stay under.
- Both SPF and DKIM, plus a DMARC record of at least p=none, with SPF or DKIM aligned to the From domain.
- Gmail and Yahoo: one-click unsubscribe on marketing mail, honoured within two days.
- Outlook.com enforces the SPF, DKIM and DMARC rule on high-volume senders and rejects the rest with 5.7.515.
- Below the threshold the rules are lighter, but unauthenticated mail still lands in spam - authenticate regardless.
This checker reads your DNS, so it covers SPF, DKIM, DMARC and MX. Alignment, unsubscribe headers, reverse DNS and complaint rates live on messages and IPs - they’re listed as “verify” items, and the Email Spam Test checks the message-level ones on a real email. DKIM is found by trying 34 common selectors, so a custom selector can read as missing. Rules and thresholds change - this reflects them as we last reviewed them.
Not sure what's blocking your mail? We audit your authentication and sending setup and fix what's wrong - usually within a few days.
How we help: Consulting · Private infrastructure · Managed mailboxes · Monthly support