Tools
Seventeen checks, each on its own page with its own explanation. Nothing here needs an account.
Authentication
The three records a receiving server checks before it trusts your mail.
SPFView SPF records and count DNS lookups against the limit of 10.Check →DKIM LookupLook up DKIM public keys by selector and check key strength.Check →DMARCCheck a domain's DMARC policy, alignment mode and reporting addresses.Check →DMARC Report ReaderUpload the .zip, .gz or .xml exactly as it arrived and read it in plain English.Open →BIMICheck the BIMI record, logo URL and VMC certificate.Check →
Deliverability
Fix the problems that send mail to spam or get your sending IP blocked.
SPF FlattenerResolve every sender into one hosted include. One DNS lookup instead of ten.Check →Blacklist CheckCheck an IP or a domain's MX servers against 14 DNS blacklists.Check →PTR LookupReverse DNS with forward confirmation, as receiving servers require.Check →MTA-STSVerify the MTA-STS DNS record and the policy file it points at.Check →TLS-RPTCheck the SMTP TLS Reporting policy record.Check →
DNS and diagnostics
Raw lookups, mail server detail, registration and certificates.
DNS LookupQuery A, AAAA, MX, TXT, CNAME, NS and SOA records from a public resolver.Check →MX InspectorResolve every MX to its IPs, verify PTR records and test port 25.Check →SSL CertificateCheck certificate expiry, the issuer chain, SANs and TLS configuration.Check →WHOISRegistration details, registrar information and domain expiry dates.Check →DNS PropagationCheck whether a DNS change has reached resolvers worldwide.Check →Zone FileGenerate a BIND-format zone file from a domain's public records.Check →Header AnalyzerPaste raw headers to trace routing, delays and authentication results.Open →