MX Record Lookup — see which mail servers accept email for any domain.

Authoritative query — no stale cache. Returns MX hostname, priority, TTL, and provider fingerprint on each row.

• Email delivery troubleshooting 'Emails to this domain are bouncing.' Step one: does the domain have MX records at all? Second: are the MX hostnames reachable? Third: does the receiving server accept your IP (SPF)?
• Verifying your mail provider You just onboarded Google Workspace or Microsoft 365 — this tool confirms your MX is pointing at the provider's servers, not still at your old provider or your own IP.
• Vendor mail-provider audit Which email platform is your vendor using? Google, Microsoft, Zoho, self-hosted? Provider fingerprint tells you in one lookup — useful for security due-diligence.
• Mail-provider migration planning Pre-lower MX TTLs before switching providers. Post-migration, verify all MX priorities are correct and no ghost entries remain from the old provider.
• Competitor infrastructure recon MX often reveals more about a company's stack than their marketing site does — legacy on-prem Exchange vs cloud, single-provider vs hybrid, in-house vs managed.

• What is an MX record? A DNS record that tells sending mail servers which host to deliver email for a domain. Every MX entry has a hostname and a numeric priority (lower = tried first). Domains without MX records can't receive email.
• Why does Google Workspace have 5 MX records? Redundancy. `aspmx.l.google.com` at priority 1 is primary; `alt1-alt4` at higher priorities are fallbacks distributed across Google's infrastructure. If aspmx.l is unreachable, sending servers fall back to alt1, alt2, etc.
• What does 'null MX' mean? An MX record of `0 .` (priority 0, target is a single dot). Explicitly declares 'this domain does not accept email' per RFC 7505. Better than no MX at all — sending servers get a clean bounce instead of retrying for days.
• Can an MX point to an IP address? No — RFC 5321 requires MX values to be hostnames that resolve to A/AAAA. Pointing MX at a bare IP is a common mistake that most receivers will reject.
• Can I use CNAME as an MX target? No — RFC 5321 prohibits MX pointing to a CNAME. The MX target must be a hostname with direct A/AAAA records. This trips up SaaS integrations that use CNAMEs everywhere.
• How is this different from MXToolbox? Same core lookup; better provider fingerprint, chains directly into SPF/DKIM/DMARC on the same domain, and no rate limits at the free tier. No signup, no cookie wall.