How to Find the Registrar for Every Email Address on a List
To find the registrar for every email address on a list, look up the registry record of the domain after each @. The bulk email domain registrar lookup does this for every address in a pasted list or CSV and gives each one a row with the registrar, registration and expiry dates, the company that runs the domain's DNS and its mail provider.
The check reads the domain, not the mailbox.
Why look up registrars on an email list
Old signups, purchased lists and long-running CRMs collect addresses at companies that have since closed or let a domain lapse. A domain with no registry record and no nameservers takes no mail, so every address at it bounces. A domain past its expiry date may be in a renewal grace period, or may be about to lapse. A list of thousands of addresses has far fewer unique domains, so checking by domain is cheap.
The by-hand way
- Take the domain after the @, for example
acme.examplefromsam@acme.example. - Find the registry that runs its ending in IANA's RDAP bootstrap file and ask it for the domain's record.
- Read the registrar, the registration date and the expiry date from the record.
- Repeat for every unique domain.
For what the record does and does not show, see what WHOIS privacy hides and what RDAP still shows.
Step 1: paste the addresses
Paste addresses one per line, or upload a CSV. Only the unique domains are sent, never the mailbox names, 10 a request.
Step 2: run the lookup
Press Find registrars. Each domain's registry is asked for its RDAP record, and its NS and MX records are read from public DNS. No mail is sent.
Step 3: read the result
| Result | What it means |
|---|---|
| Registered | The registry has a record; the registrar and dates are in the row |
| Past its expiry date | The listed expiry has passed; this can be a grace period |
| No registry record | The registry returned nothing; the row says whether DNS still has the name |
| Registry gives no registrar | The ending publishes no RDAP |
The CSV carries the registrar, dates, DNS host and mail provider beside each address. Addresses at domains with no record and no DNS are left out of the list handed on to the mailbox check.
What this check cannot do
- It checks the domain, not the mailbox.
- A registry answer of no record is not proof a name is free.
- Up to 100 unique domains a run without an account, 500 signed in. Subdomains are reduced to the registered name.
For bare domains use the domain registrar lookup, and to understand the difference between who registers, who hosts the DNS and who hosts the site, read registrar vs DNS host vs web host.
Next: the rest of the list
For the addresses that remain, use the verify page: the first 100 checks are free with a Google sign-in, no card.
Try it now
Paste your list into the bulk email domain registrar lookup at simpleverifier.com.
Common questions
How do I find the registrar for every email address on a list?
Take the domain after the @ in each address and look up its registry record. A bulk email domain registrar lookup does that for every address in a pasted list and returns registrar, registration date, expiry date, DNS host and mail provider.
Where does the registrar come from?
From the registry's RDAP record, the structured successor to WHOIS. Country endings that publish no RDAP show the registrar as not given.
Does a passed expiry date mean the domain has lapsed?
Not always. It can be a renewal grace period or a stale record. Recheck those rows later.
Can an address at a registered domain still bounce?
Yes. A registered domain can still hold a closed mailbox. The tool checks the domain, not the mailbox.
Is the lookup free?
Yes. Up to 100 unique domains a run with no account, and up to 500 after a free Google sign-in.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.