Bulk Sender Compliance Checker
Check your domain against Google, Yahoo, and Microsoft's 2026 bulk sender requirements — SPF, DKIM, DMARC, and the manual checks they also require.
Who counts as a "bulk sender"?
Google, Yahoo, and Microsoft classify anyone sending 5,000+ emails a day to their users as a bulk sender — subject to stricter authentication rules than smaller senders. Below that threshold the requirements are recommended, not enforced, but failing them still hurts deliverability.
What this tool checks
- • SPF, DKIM, and DMARC published in DNS — verified automatically
- • DMARC alignment, one-click unsubscribe headers, and spam complaint rate — flagged for manual verification, since they can't be confirmed from DNS alone
What this tool tests, and what it cannot
The checker evaluates six requirement rows. Three are tested automatically from public DNS: SPF, DKIM and DMARC. The other three are marked manual because they cannot be read from DNS: DMARC alignment on real mail, one-click unsubscribe headers, and spam complaint rate. The tool does not guess at those. It lists them so they are not forgotten.
The overall status is the worst of the three automated results. The tool treats the domain as compliant unless one of them fails, so a warning (for example DMARC at p=none, or a single DKIM selector) still counts as compliant here. A warning is still worth fixing, but for Google and Yahoo a DMARC policy of p=none satisfies the minimum.
| Requirement row | How it is tested | Passes when |
|---|---|---|
| SPF published and authenticating | DNS lookup of the SPF record | One record, ends in -all, fewer than 8 DNS lookups, no ptr mechanism. ~all gives a warning. No record, multiple records, +all, ?all or more than 10 lookups fail |
| DKIM signing key published | Probes common selectors for your domain and mail provider | Two or more valid keys. One valid key or test-mode keys give a warning. Revoked-only keys, or none detected, do not pass |
| DMARC record published | DNS lookup of _dmarc | Policy is quarantine or reject at pct=100 with a rua address. p=none, pct below 100 or no rua give a warning. No record fails |
| DMARC alignment on sent mail | Manual | Read DMARC aggregate reports or a real message's Authentication-Results |
| One-click unsubscribe | Manual | List-Unsubscribe and List-Unsubscribe-Post present and signed by DKIM |
| Spam complaint rate under 0.3% | Manual | Google Postmaster Tools or Microsoft SNDS |
What Google, Yahoo and Microsoft require
Google and Yahoo began enforcing their bulk-sender rules in February 2024. Microsoft began enforcing authentication requirements for high-volume senders to Outlook.com consumer addresses in May 2025. The details below reflect the published requirements as we understand them. Providers update their rules, so confirm against their current documentation before relying on any single figure.
- Volume threshold: Google defines a bulk sender as one sending close to 5,000 or more messages a day to personal Gmail accounts, and once you reach it, you stay in that category. Yahoo and Microsoft use a similar 5,000 per day figure.
- All senders to Gmail need SPF or DKIM, valid forward and reverse DNS for sending IPs, TLS, and properly formatted messages.
- Bulk senders to Gmail and Yahoo need SPF, DKIM and a DMARC record of at least p=none. The domain in the From header must align with the SPF or DKIM domain.
- Marketing and subscription mail needs one-click unsubscribe as defined in RFC 8058, and unsubscribe requests should be honored within two days.
- Spam rate in Google Postmaster Tools should stay below 0.10%, and must never reach 0.30%.
- Microsoft's consumer-mailbox rules centre on SPF, DKIM and DMARC with alignment. Non-compliant mail may be rejected with an error such as 550 5.7.515.
Checking the three manual items
DMARC alignment. SPF and DKIM passing is not enough. DMARC needs the domain that passed to match the From domain. Send a test message to a Gmail address, open Show original and look for dmarc=pass with header.from=yourdomain.com. For ongoing proof, read your DMARC aggregate reports, which show pass rates by sending source.
One-click unsubscribe. Marketing mail must carry both headers below, and both should be covered by your DKIM signature (RFC 8058). The URL must work as an HTTPS POST without any login or further confirmation page. Most email service providers add these automatically if the setting is enabled, but transactional systems and in-house senders often do not.
Headers expected on subscription mail
List-Unsubscribe: <https://example.com/unsubscribe/abc123>, <mailto:unsubscribe@example.com?subject=unsubscribe> List-Unsubscribe-Post: List-Unsubscribe=One-Click
To confirm they are present, open the raw headers of a received message (Show original in Gmail) and search for List-Unsubscribe. The Email Header Analyzer does not currently summarize these two headers, so read them in the raw text.
Spam complaint rate. Register your sending domain in Google Postmaster Tools, which requires proving ownership with a DNS TXT record. It reports spam rate, authentication success and reputation for mail to Gmail. Data appears only when you send enough volume. Microsoft's SNDS provides comparable data for mail to Outlook.com for IP addresses.
Common failures and fixes
| Result | Cause | Fix |
|---|---|---|
| No SPF record | Domain never published one | Publish a single v=spf1 record listing every sender, ending in -all |
| SPF fail: multiple records | A new service added a second TXT record | Merge all mechanisms into one record |
| SPF fail: over 10 lookups | Too many include: chains | Remove unused services or restructure. See the SPF lookup guide |
| DKIM not detected | Custom selector, or DKIM not enabled | Enable signing in each sender and publish its key. Confirm the selector from a header |
| No DMARC record | Never published | Start with p=none and a rua address, then review reports |
| DMARC warning, p=none | Monitoring only | Acceptable as a minimum, but plan to move to quarantine or reject |
| Messages rejected despite passing here | Alignment failure, or a spam rate above 0.3% | Check aggregate reports and Postmaster Tools |
Before you reach the threshold
- Inventory every system that sends mail as your domain: your mailbox provider, marketing platform, CRM, billing system and support desk.
- For each, authenticate with your own domain (custom DKIM, custom bounce domain where available) so alignment passes.
- Publish DMARC with rua and read the reports for two to four weeks before tightening policy.
- Add List-Unsubscribe and List-Unsubscribe-Post to marketing streams, and test an unsubscribe end to end.
- Register in Postmaster Tools and watch spam rate and authentication success weekly.
- Separate marketing and transactional mail onto different subdomains so a complaint problem in one does not damage the other.
Limits of this check
- It detects DKIM by probing common selector names. A custom selector will not be found and shows as not detected.
- It cannot see your sending volume, so it cannot tell whether the bulk-sender rules strictly apply to you. Below 5,000 a day they are not enforced in the same way, but they are still best practice.
- A pass is a necessary condition, not a guarantee. Reputation, content and list quality still decide inbox placement.
Related tools and guides
Frequently Asked Questions
What are the Google, Yahoo, and Microsoft bulk sender requirements?
Since 2024, Google, Yahoo, and Microsoft require anyone sending 5,000+ emails a day to their users to: publish valid SPF and DKIM records, publish a DMARC record with alignment, keep spam complaint rates under 0.3%, and support one-click unsubscribe on promotional and subscription email. Missing any of these can lead to messages being rejected or sent to spam.
Do these requirements apply to me if I send fewer than 5,000 emails a day?
The 5,000/day threshold defines who is formally classified as a bulk sender, but SPF, DKIM, and DMARC improve deliverability for senders of any size. Smaller senders aren't penalized for missing one-click unsubscribe or spam-rate thresholds, but adopting the same standards early avoids problems if volume grows.
Why can't this tool check one-click unsubscribe or spam complaint rate automatically?
SPF, DKIM, and DMARC are published in public DNS, so they can be checked instantly from a domain name alone. One-click unsubscribe depends on headers inside an actual sent message, and spam complaint rate is only visible inside mailbox-provider tools like Google Postmaster Tools — neither is derivable from DNS records.
What is DMARC alignment and why is it checked separately from having a DMARC record?
Publishing a DMARC record is not the same as passing DMARC on real mail. Alignment means the domain authenticated by SPF or DKIM matches the domain shown in the From: header of an actual message. Confirming alignment requires reviewing DMARC aggregate reports or a live message, not just the DNS record.