SPF, DKIM & DMARC Checker
Verify your domain's email authentication records and get actionable recommendations to improve deliverability
What are SPF, DKIM, and DMARC?
SPF
Sender Policy Framework
Lists which mail servers are authorized to send email for your domain. Receiving servers check SPF to verify the sender's IP address is permitted.
DKIM
DomainKeys Identified Mail
Adds a cryptographic signature to every outgoing email. Receiving servers verify this signature to confirm the message was not tampered with in transit.
DMARC
Domain-based Message Authentication
Ties SPF and DKIM together with a policy that tells receivers what to do when authentication fails: nothing, quarantine, or reject the message.
Why Email Authentication Matters
Send emails that land in inboxes?
Stack0 Email handles authentication, deliverability, and analytics so you can focus on content.
Related Tools
Need programmatic access? Stack0 Mail lets you automate this at scale.