Google, Yahoo and Microsoft sender requirements checker
Gmail, Yahoo and Outlook.com now refuse or junk bulk email from domains without SPF, DKIM and DMARC. Check a domain against each provider's rules in one go.
Check a sending domain
We look up public DNS only, and don't keep a record of the domains you check.
What each provider requires
All three providers now set minimum standards for email arriving at their personal mailboxes. The bar is higher for bulk senders: roughly 5,000 or more messages a day to that provider's users. Google counts a domain as a bulk sender for good once it has crossed that line.
Gmail
Every sender needs SPF or DKIM, valid forward and reverse DNS on the sending server, TLS, and a spam rate under 0.3%. Bulk senders also need both SPF and DKIM, a DMARC record (p=none is enough), a From domain aligned with SPF or DKIM, and one-click unsubscribe on marketing email, honoured within two days. Source: Google's email sender guidelines and FAQ.
Yahoo
Every sender needs SPF or DKIM, valid forward and reverse DNS and a spam rate under 0.3%. Bulk senders also need both SPF and DKIM, a valid DMARC policy with the From domain aligned, and a working one-click unsubscribe, honoured within two days. Source: Yahoo's sender best practices.
Outlook.com (Microsoft)
Domains sending over 5,000 messages a day to Outlook.com, Hotmail and Live addresses must pass SPF and DKIM and publish DMARC at p=none or stricter, aligned with SPF or DKIM. Since 5 May 2025, Microsoft says, failing mail is rejected with 550 5.7.515 Access denied. Microsoft also recommends a working unsubscribe link and a From or Reply-To address that can receive replies. Source: Microsoft's announcement.
What this checker can and can't see
SPF, DKIM and DMARC records are public, so we check them directly. Alignment, reverse DNS, TLS and unsubscribe headers belong to real messages and the server that sends them. Send one email to the free email test to check those. Spam rates are only visible in Google Postmaster Tools and Yahoo's Sender Hub.
Do this for every client, every day
- All nine checks on every client domain, daily, graded A to F
- Alerts by email or webhook when a grade drops or a record changes
- A monthly report card for each client, with your logo on it
- Hosted DMARC, SPF, DKIM and MTA-STS, so fixes don't wait for a DNS login
Start a free 28-day trial: up to 3 domains, no card needed.
Keep going
- Google, Yahoo and Microsoft sender requirements explainedThe guide
- No SPF recordHow to fix it
- DKIM not foundHow to fix it
- No DMARC recordHow to fix it
- DMARC p=none or pct below 100How to fix it
- DMARC checkerSee a domain's DMARC policy in plain English, and where its reports go.
- Email header analyserPaste an email's headers to see its route, SPF, DKIM and DMARC results and alignment.
- DKIM checkerFind a domain's DKIM keys, with or without the selector, and check their size.
- Free domain checkerAll nine checks on a domain, with a grade from A to F.
- Report cardsWhat your clients get each month, with your logo on it.
Questions
Do these rules apply if I send less than 5,000 emails a day?
Partly. Gmail and Yahoo ask every sender for SPF or DKIM, reverse DNS and a low spam rate, and Gmail asks for TLS. SPF, DKIM and DMARC are worth having at any volume.
Is DMARC p=none really enough?
For these rules, yes. But p=none doesn't stop anyone spoofing the domain; quarantine or reject does, once every real sender passes.
What does 'aligned' mean?
The domain that passed SPF (the Return-Path) or DKIM (the d= in the signature) matches the From domain, or shares its organisational domain.
Why can't you check alignment from the domain alone?
It depends on how each service sends your email. Send a message to the free email test and it checks the real thing.
What happens if a domain doesn't comply?
Gmail and Yahoo may junk or reject the mail. Microsoft says it rejects non-compliant bulk mail with error 550 5.7.515.
Keep every client's domain compliant, every day.
Start a free 28-day trial: up to 3 domains, no card needed.