MailFabric

Email deliverability checker

Check a domain's SPF, DKIM, DMARC, MX and blocklist status. Get a score out of 10 and the exact records to fix. Free, no signup.

Add a DKIM selector

The s= value in the DKIM-Signature header of an email you sent. Needed for providers that use a selector unique to your domain, such as Amazon SES, SMTP2GO and Postmark. Up to 3, separated by commas.

We only read public DNS records (and the MTA-STS policy file if you publish one). Nothing is sent to your domain, and results are kept for 10 minutes so repeat checks are fast.

What this checks

SPF
Lists the servers allowed to send mail for your domain. Must be a single record using 10 DNS lookups or fewer.
DKIM
A signature on every message that proves it came from you and was not changed. Keys should be 2048 bits.
DMARC
Tells receivers what to do with mail that fails SPF and DKIM, and where to send reports. Required by Gmail and Yahoo for bulk senders.
MX
Where mail for your domain is delivered, including replies and bounces.
MTA-STS
Requires senders to use TLS when delivering mail to you. Optional.
Blocklists
Checks your mail servers and domain against public spam blocklists. A list that refuses our lookup is shown as not checked, never as clean.

Every domain starts at 10. Failures and warnings subtract points; optional features you have not set up and anything we could not check do not. A score of 9 or more is excellent.

MailFabric
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