Instantly look up and validate the MX records for any domain, mail server hostnames, priorities, IP resolution, and PTR records.
Type example.com, no https:// or www needed.
All DNS queries run server-side in parallel. Each MX hostname is resolved to its IPs and a PTR lookup runs on each.
Hostname, priority, resolved IPs, PTR record, and TTL for every MX, plus an overall verdict.
Unresolvable hostnames, missing fallbacks, CNAME targets, and PTR mismatches come with specific recommendations.
Two or more MX records with sensible priorities, all resolving correctly. Monitor periodically to make sure records stay correct.
Mail still works but something needs attention, a single MX with no fallback, a PTR mismatch, or an MX pointing at a CNAME.
No MX records exist, the domain cannot receive email and all incoming messages bounce. Add MX records with your DNS provider immediately.
An MX (Mail Exchange) record is a DNS record that specifies which mail servers receive email on behalf of a domain. Each record pairs a hostname with a priority number, lower numbers are tried first.
Without a valid MX record, email sent to your domain bounces immediately with a permanent delivery failure.
Multiple MX records with different priorities keep mail flowing when the primary server is offline, senders fall over automatically.
MX records handle inbound routing. To protect outbound mail from spoofing, pair them with SPF, DKIM, and DMARC.
MX changes take up to 48 hours to propagate globally. Lower the TTL before planned migrations to shrink the cutover window.
Lower number = higher priority. Mail is delivered to the lowest-priority server first; equal priorities share traffic roughly equally. A common setup is 10 for primary and 20 for backup.
Receiving servers verify that the IP sending or accepting mail maps back to a legitimate hostname. A missing or mismatched PTR on your mail server IP gets mail flagged as spam.
No, RFC 2181 requires MX targets to be hostnames with direct A/AAAA records. Many servers tolerate CNAMEs, but it is a misconfiguration that can cause unpredictable delivery failures.
It works, but you have no failover: if that server goes down, senders queue and eventually bounce mail. Add a second MX with a higher priority number as a backup.
Resolvers cache MX records for the TTL duration, typically 1 to 48 hours worldwide. Use our DNS Propagation Checker to watch the rollout in real time.
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SenderSignal monitors these signals continuously: 48 blacklists, SPF, DKIM, DMARC, TLS and more, with alerts in Slack, email and signed webhooks.