List a domain's mail servers in priority order and check that each one resolves.
Email tools
Check and build MX, SPF, DKIM and DMARC records for mail routing and sender authentication.
Validate an SPF record and count its DNS lookups against the limit of 10.
Fetch a DKIM key by selector and check its format and key length.
Read a DMARC policy in plain English and spot settings that weaken it.
Build an SPF record from the services that send email for your domain.
Create a DMARC record and plan a safe move from monitoring to enforcement.
Paste raw headers to trace each delivery hop and read SPF, DKIM and DMARC results.
The records behind email delivery
MX: where your mail goes
MX records tell other servers where to deliver mail for your domain. If they point to the wrong place, mail bounces or vanishes. The MX Lookup shows them in priority order and checks each server has an address.
SPF, DKIM and DMARC: proving it is really you
SPF, DKIM and DMARC help receivers authenticate a message and relate its identities to the visible From domain. Provider requirements differ for all senders and bulk senders; passing authentication does not guarantee inbox placement. Check published records with the SPF, DKIM and DMARC checkers, then confirm actual received-message headers.
When a message has already gone wrong
Paste the headers of the problem message into the Email Header Analyzer. It shows which checks failed at the receiving end and where delivery was delayed. For a full walk-through, read emails going to spam.