hellosoftware

Free tool

Email security checker

See whether a domain is protected against people sending email in its name, and what to fix if it isn't.

For example example.com, or an email address

Found after s= in a delivered email's DKIM-Signature header

What this checks

  • SPF

    A TXT record listing the servers allowed to send email for your domain. Receivers check the sending server against it. SPF allows at most 10 DNS lookups, counting everything inside each include, so we follow the includes and count them.

  • DKIM

    Your email provider signs each message, and publishes the public key in DNS under a selector name. Selectors can't be listed from DNS, so we try the common names and any selector you give us.

  • DMARC

    A TXT record at _dmarc that tells receivers what to do when a message fails SPF and DKIM (none, quarantine or reject) and where to send reports. Without it, anyone can put your domain in the From line.

  • MX, MTA-STS and TLS reporting

    MX records say which servers receive your mail. MTA-STS and TLS reporting are optional extras that make other servers use encrypted connections when delivering to you, and tell you when that fails.

Nothing you enter is stored. Results come from public DNS and one request to the address you give.

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