Email Tools
Mail Server Lookup
Look up a domain's mail server hostnames, IP addresses, and reverse DNS.
Enter a domain to look up its mail server hostnames, IP addresses, and reverse DNS.
JustChecker tracks your mail server configuration continuously.
Frequently Asked Questions
Beyond just the MX hostnames, this resolves each mail server to its actual IP address(es) and reverse DNS hostname, giving a fuller picture of the underlying mail infrastructure behind your domain's MX records.
Many receiving mail servers check that a sending server's IP has a matching, legitimate-looking reverse DNS (PTR) record as a basic spam-fighting signal - a missing or mismatched PTR record can hurt deliverability even with otherwise correct SPF/DKIM/DMARC.
Often yes - the resolved IP addresses and reverse DNS hostnames frequently reveal a recognizable provider naming pattern (Google, Microsoft, or a dedicated mail hosting company), even without checking WHOIS separately.
This is normal for redundancy or load distribution across a provider's mail infrastructure, or if you have multiple MX records each pointing to a different physical server for failover purposes.
Not necessarily a fatal problem, but it's worth reviewing - some receiving servers weigh mismatched or missing reverse DNS more heavily than others when making spam-filtering decisions, so aligning it where you control the infrastructure is good practice.
No - WHOIS provides domain registration information; this tool resolves the actual technical mail server infrastructure (hostnames, IPs, reverse DNS) your MX records point to, which is a completely different layer of information.