Is it safe to paste my email headers here?

Yes. The analysis happens in your browser and nothing is uploaded. Headers can contain IP addresses and server names, so avoid sharing them publicly.

Why is there no Authentication-Results header?

That header is added by the receiving mail server. If you copied headers from a message in your Sent folder, or from a client that strips it, it will be missing. Use the original copy from the recipient's inbox.

What does a big delay between hops mean?

That server held the message before passing it on, often because of greylisting, queueing or scanning. The slowest hop is the one to investigate.

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Free email header analyzer

Paste the raw headers of any email to see who really sent it, the servers it passed through, how long each hop took, and whether it passed SPF, DKIM and DMARC.

How to get an email's full headers

In Gmail open the message, choose the three-dot menu and then Show original. In Outlook open the message, choose File, Properties and copy the Internet headers. In Apple Mail choose View, Message, All Headers. Copy everything above the message body and paste it into the box.

What the analyzer shows

It lists the main fields (From, To, Subject, Date, Return-Path, Reply-To and Message-ID), reads the Authentication-Results header the receiving server added to report SPF, DKIM and DMARC, and walks through the Received headers from the first server to the last with the time each hop took. Findings point out common problems such as a failed check, a Reply-To that goes to a different domain, or a DKIM signature that does not match the From domain.

Everything runs in your browser. The headers you paste are never sent to MailSure.

Reading the authentication results

SPF checks that the sending server is allowed to send for the domain. DKIM checks a cryptographic signature added by the sending domain. DMARC says what to do when those checks fail and requires one of them to align with the visible From domain. If any show fail or none, use the SPF, DKIM and DMARC checkers to inspect the domain's DNS records.

Frequently asked questions

Is it safe to paste my email headers here?: Yes. The analysis happens in your browser and nothing is uploaded. Headers can contain IP addresses and server names, so avoid sharing them publicly.
Why is there no Authentication-Results header?: That header is added by the receiving mail server. If you copied headers from a message in your Sent folder, or from a client that strips it, it will be missing. Use the original copy from the recipient's inbox.
What does a big delay between hops mean?: That server held the message before passing it on, often because of greylisting, queueing or scanning. The slowest hop is the one to investigate.