Email Header Analyzer

A message header analyzer turns the raw technical headers of an email into a readable report. It shows whether the message passed SPF, DKIM and DMARC, lists every server it passed through with the delay at each hop, and surfaces spam filter scores, so you can see why an email was delayed, rejected or sent to spam.

The Microsoft Message Header Analyzer is Microsoft's own tool for reading email headers, available as an Outlook add-in and a web page. It is built around Exchange and Microsoft 365 diagnostics. This email header analyzer reads the same headers, including Microsoft's SCL and antispam fields, and works with mail from any provider.

Yes, this message header analyzer is safe to use because it runs entirely in your browser. The headers you paste are never sent to Mailwarm or stored anywhere. Headers can contain email addresses, IP addresses and server names, so avoid pasting them into tools that upload them to a server unless you trust the provider.

To check a message header, open the original source of the email in your mail client and copy the header section. In Gmail choose Show original, in Outlook open the message details or properties, and in Apple Mail view the raw source. Paste the headers into the analyzer above to read them.

SCL stands for spam confidence level, a score Microsoft 365 and Exchange add to every incoming message. A value of -1 means filtering was skipped, for example for a safe sender. 0 and 1 mean the message isn't spam. 5 and 6 mean spam, and 9 means high-confidence spam, which usually goes to junk or quarantine.