Email header analyzer
Use this email header analyzer to read delivery hops, delays and receiver authentication results. Inspect alignment and ARC assertions without uploading your headers.
Free, no account. Runs in your browser: nothing you paste leaves this page.
Email deliverability checks
Check the sending identity, domain policy, receiving servers and an actual received message together. These checks explain configuration; they cannot certify delivery to an inbox.
- SPF
- Authorize your sending IP and trace the DNS lookup budget.
- DMARC / DKIM
- Check policy, alignment settings, reporting permissions and public keys.
- MX
- Inspect incoming servers, addresses, reverse DNS and the public blocklist.
- Email headers
- Read actual receiver results, forwarding assertions and hop delays locally.
- DKIM
- Read the public key for a selector, or try common provider selectors.
- Blocklists
- Check mail server addresses on DNS blocklists, with removal steps.
- MTA-STS
- Check the TLS policy for incoming mail, its MX match and TLS reports.
- BIMI
- Check the BIMI record, the SVG logo, the certificate and DMARC readiness.
Google and Yahoo bulk sender requirements
Requirements checked 2026-10-12. Google applies its bulk rules above 5000 messages per day to personal Gmail accounts. Yahoo describes bulk senders without publishing the same numeric threshold.
- Publish SPF and sign with DKIM. Publish DMARC with at least p=none, and align the visible From domain with a passing SPF or DKIM identity.
- Use valid forward and reverse DNS and correctly formatted messages. Google also requires TLS transport. Keep reported spam rates below 0.3 percent.
- Marketing and subscribed messages need one-click unsubscribe headers plus a visible unsubscribe link. Honor unsubscribe requests within two days.
- Google requires RSA DKIM keys of at least 1024 bits and recommends 2048 bits. A DNS key check does not prove that outgoing mail is signed.
Spam rate, unsubscribe behavior and real SMTP TLS are outside a DNS check. Verify them with your mail service and a received message.
Google sender guidelinesYahoo sender requirementsYahoo bulk sender definition
An email header analyzer reads the technical headers that mail servers add to every message. Paste them to see the Received chain in order with the delay at each hop, the SPF, DKIM and DMARC results, and whether the From, Return-Path and Reply-To addresses agree. The analysis runs in your browser, and the headers never leave it.
How to use this analyzer
- Copy the raw headers
- In Gmail, open the message, choose More and then Show original. In Outlook on the web, choose View and then View message details. In Apple Mail, choose View, Message, All Headers. Copy everything above the message text.
- Read the path
- Received headers are listed from the first server to your inbox, with the time each step took. A long delay usually points to a queue or a spam filter at that hop.
- Check the results
- The topmost Authentication-Results header, added by the server that delivered the message to you, counts most. A From domain that differs from the Return-Path or Reply-To is normal for mailing services, and worth a second look in an unexpected message.
Questions about this analyzer
Check your business in AI answers
Headers show how one message travelled. The free AI visibility scan shows how ChatGPT and other assistants describe your business, and what to fix first.