Bulk MX reverse DNS checker: does each MX address have a PTR that matches?
In short: Paste domains and see each one's lowest-priority MX hosts resolved to an IP, the IP's PTR names read, and each name checked for forward confirmation and for matching the MX host. Limit: Only DNS is checked. It doesn't connect to the mail servers or read their HELO name.
A bulk MX reverse DNS checker looks at the mail servers behind a list of domains. Paste up to 100 domains, or 500 after a free Google sign-in, and each row shows the domain's lowest-priority MX hosts, each host's IPv4 address, the PTR names that address returns, whether each name resolves back to it, and whether it equals the MX host. DNS only. Download the CSV.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. Check your list free nowSee pricing
Sample result
mx.acme.example's address has a PTR that matches; the address behind mail.initech.example has none.
- MX host
- mail.initech.example
- Address
- 198.51.100.24
- PTR names
- None
What this means for you
A missing PTR matters most when the same server also sends your mail.
- Three lowest-priority MX hosts
- PTR read and forward-confirmed
- Match with the MX name shown
- No connection to the servers; CSV out
- PTR
- MX
- FCrDNS
By SimpleVerifier Team · Last updated
Auditing the email DNS of a domain list?
- Paste the domains here: up to 100 a run, or 500 after a free Google sign-in. Filter to the rows that need a fix and download the CSV.
- Upload or paste it at /verify. Every address gets a live mailbox check, and the first 100 email checks are free with a Google sign-in, no card.
How do I check the reverse DNS of many domains' MX servers?
- Paste domains, email addresses or URLs, one per line, up to 100 a run or 500 after a free Google sign-in.
- Press Check MX reverse DNS. Each domain's MX records are read, then the three lowest-priority hosts are resolved to an IPv4 address and that address's PTR record is read and confirmed, 5 domains a request. No connection is made to the mail servers.
- Read each row: PTR matches MX host, Forward-confirmed, PTR not confirmed, No PTR record, No MX to check, or Lookup failed, with every host's result.
- Filter to the rows that need a fix and download the CSV.
Example
- You enter
- Three domains:
acme.example(self-hosted MX with a matching PTR),globex.example(a hosted provider's MX) andinitech.example(an MX address with no PTR). - You get
- acme.example: PTR matches MX host, the PTR name resolves back to the IP. globex.example: Forward-confirmed, a valid PTR under a different name. initech.example: No PTR record, with the IP shown. Download the CSV.
- Limits
- Up to 100 a run without an account and 500 when signed in with Google, counted over a minute. 5 domains a request; DNS only, IPv4, the three lowest-priority MX hosts.
What is reverse DNS for a mail server?
Forward DNS turns a hostname into an IP address. Reverse DNS does the opposite: the IP's PTR record, stored under in-addr.arpa, names a host. Receiving mail servers often look up the PTR of a connecting IP, and many treat an IP with no PTR, or one that doesn't resolve back to it, as a sign of a badly run or compromised sender. RFC 1912 recommends that every IP with a hostname has a matching PTR.
Forward-confirmed reverse DNS (FCrDNS) is the stronger test: the PTR name must resolve, in turn, to the original IP. This tool runs that test on each MX address.
Does an MX server's PTR need to match its MX hostname?
Not by any rule for receiving mail. An MX host receives connections; the PTR check matters most for servers that connect out. It becomes relevant for MX hosts when the same machines also send your mail, which is typical for a self-hosted server and uncommon behind a large hosted provider.
So read the three outcomes this way. PTR matches MX host is the tidy case. Forward-confirmed means the address has a valid PTR under a different name, as hosted providers often have. PTR not confirmed and No PTR record are the ones worth a look if the server also sends mail. To check the PTR of a list of sending IPs rather than MX hosts, use the bulk reverse DNS lookup.
What does the check cover?
The three MX hosts with the lowest preference numbers, the first IPv4 address of each, and up to five PTR names per address, each forward-checked with an A query. Private and reserved addresses are skipped, and IPv6 isn't covered.
The result is a snapshot. A PTR record belongs to whoever owns the IP address block, usually the hosting provider, so changes are made in their control panel, not in your domain's DNS. See reverse DNS and PTR records for email for how to ask for one.
Who uses this tool, and for what?
- Self-hosted mail operators
- Find MX addresses with no PTR or one that doesn't resolve back, before a receiver does.
- Hosting and MSP teams
- Audit client mail servers after a migration or an IP change.
- Deliverability consultants
- Add a reverse DNS column to a domain audit and export it as CSV.
- IT administrators
- Check that a mail relay's address and hostname still agree.
What can’t this tool tell you?
- Only DNS is checked. It doesn't connect to the mail servers or read their HELO name.
- Only IPv4, and the first address of each of the three lowest-priority MX hosts.
- A missing PTR on a hosted provider's shared MX name is common and not a fault of the domain.
- Up to 100 domains a run without an account, 500 signed in.
Common questions
- How do I check the PTR record of many MX servers?
- Paste the domains into a bulk MX reverse DNS checker like this one. It finds each domain's MX hosts and IPs, reads the PTR and confirms it resolves back, with a CSV of the results.
- Is this bulk MX reverse DNS checker free?
- Yes. It is a free tool: up to 100 domains a run with no account, and up to 500 a run when you sign in with Google, with no card.
- What is forward-confirmed reverse DNS?
- The PTR record of an IP names a host, and that host's A record points back to the same IP. Both directions agree.
- Why does a large provider's MX show forward-confirmed but not matching?
- Providers run many servers behind a few MX names, so an address's PTR often names the individual machine rather than the shared MX name. That is normal.
- Does this tell me whether my domain's mail is deliverable?
- No. It checks one DNS signal on the receiving side. Deliverability of a mailbox is checked by verifying the address itself.
- Who can add a PTR record?
- The owner of the IP address block, which is normally your hosting or network provider, not your DNS host.
Sources
A tidy list can still be full of dead addresses.
Extracting, deduplicating and syntax checks all work on the text of an address. None of them can tell whether the mailbox exists. Only the server that hosts it can answer that, through an SMTP check, and that is what the paid product does.
- Upload the cleaned file as it is: CSVs up to 100,000 rows
- A real SMTP mailbox check on every row, with catch-all detection
- Small list? Starter at $9/mo covers 2,500 emails a month, cancel anytime
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.