How to Find Where Each Domain's Email Is Hosted in Bulk

To find where a domain's email is hosted, look up its MX records, then follow each MX host to its IP address and the network that runs it. The bulk mail server lookup does that for up to 100 domains or email addresses a run, or 500 after a free Google sign-in, and returns up to three MX hosts per domain with the IP, reverse DNS (PTR) name, network (ASN) and provider.

It reads DNS only. It never connects to a mail server and never says whether a mailbox exists.

Why look at mail hosting across a list

Knowing who hosts the mail on a list of company domains helps you segment by provider, spot domains that point at a single server, and find leftovers on old providers. For a prospect list it also shows which domains have no usable mail setup before you send anything.

The by-hand way

1. Look up the domain's MX records with the MX lookup. Lower priority numbers are tried first.
2. Look up the A record of each MX hostname to get its IP address.
3. Run a reverse lookup on the IP with the reverse DNS lookup to see its PTR name.
4. Look up which network announces the IP (its ASN) to see who runs it.

That is four lookups per domain, which is why it does not scale past a handful. The post on reverse DNS of MX servers explains why the PTR name matters.

Step 1: paste the domains

Paste domains or email addresses, one per line, up to 100 a run or 500 after a free Google sign-in.

Step 2: run the lookup

Press Look up mail servers. Each domain's MX records are read, then the first three hosts' addresses, PTR names and networks, 10 domains a request.

Step 3: read and filter the rows

Each row shows the provider, every MX host in priority order with its IP, PTR and network, and flags for a single MX host or all hosts on one network. Filter by network or provider, then download the CSV with one line per MX host.

For just the provider name per address, the bulk email provider lookup is the lighter tool.

What this check cannot do

• Only the first three MX hosts of each domain are followed.
• A hostname or network points to a provider, but a domain can route mail through a filtering service in front of its real mailboxes.
• It does not test whether a server accepts mail, or whether any mailbox exists.
• The run limit is 100 a run without an account and 500 after a free Google sign-in.

To see which domains have no mail server at all, use the bulk MX lookup.

The step after this

Knowing where mail is hosted does not tell you which mailboxes are open or closed. Upload it at the verify page: a Google sign-in gets you the first 100 email checks without a card. The result per address is valid, risky or invalid plus the reason, with no email sent to anyone. If the list is large or comes back every month, see bulk email verification.

Try it now

Paste your domains into the bulk mail server lookup.