Email Security Analysis of cert.is

Complete verification of cert.is's SPF, DKIM, DMARC, and MTA-STS records. Find out if this domain is protected against email spoofing.

Last updated: April 15, 2026

90A

This domain is protected against spoofing

v=spf1 include:_spf.cert.is include:spf.protection.outlook.com mx -all

Selectors: selector1

v=DMARC1; p=reject; rua=mailto:re+lwvfyw2anak@dmarc.postmarkapp.com; pct=100; sp=none; aspf=r;

charon.cert.is, styx.cert.is

Missing

No record found

1Add MTA-STS to enforce TLS encryption for incoming emails
Without MTA-STS, an attacker performing a man-in-the-middle attack can downgrade the connection between mail servers to plaintext, intercepting emails in transit. MTA-STS tells sending servers to only deliver via TLS with a valid certificate, preventing downgrade attacks.

Run a live analysis

The results above are updated daily. For an instant check of cert.is, run a live analysis.

Understand how SPF defines which servers are authorized to send emails for a domain.

Discover how DKIM cryptographically signs your emails to guarantee their authenticity.

Learn how DMARC orchestrates SPF and DKIM to protect your domain.

Learn how MTA-STS enforces TLS encryption to protect your emails in transit.

Compare the three protocols and understand how they work together.