MX Inspector
MX Inspector
Check MX records, reverse DNS, forward confirmation, and port 25 connectivity.
Enter a domain above to inspect its mail exchangers
About this tool
- What are MX records?
- Mail Exchanger records. DNS entries that specify which mail servers are responsible for accepting email on behalf of a domain, listed in priority order — the server with the lowest priority number is tried first.
- Why is port 25 checked?
- Port 25 is the standard SMTP port used for server-to-server email delivery. If port 25 is blocked or unreachable, your mail server cannot receive email from other servers.
- What is a PTR record and why does it matter?
- A PTR (pointer) record is reverse DNS — it maps an IP address back to a hostname. Forward-confirmed PTR means the hostname also resolves back to that IP. Missing or mismatched PTR records cause many receiving servers to reject or spam-folder your mail.
- What does 'forward mismatch' mean?
- The IP's PTR record points to a hostname, but that hostname does not resolve back to the same IP. This asymmetry is a common spam signal and may cause mail to be rejected or flagged.