Mail configuration check
Check the MX, SPF and DMARC records of a domain and find common mistakes such as multiple SPF records, +all or a missing DMARC policy.
About this check
SPF lists which servers may send mail for a domain, DMARC tells receivers what to do with mail that fails SPF or DKIM, and MX records say where mail for the domain is delivered. All three are public DNS records.
Other tools: Geofeed checker, DNS record lookup, TLS certificate check, HTTP header check, DNS blocklist check, Subnet calculator.