Email domain replacer: change old-company.com to new-company.com across a whole list
In short: Upload a list, write one line per domain change and download the file. The part before the @ is never touched, and addresses that now repeat are counted. Limit: It rewrites text and cannot tell whether the new mailbox exists.
Upload a CSV or .xlsx file, or paste it with a header row. Pick the email column and write one change per line, such as old-company.com -> new-company.com. Choose whether subdomains change too. Every matching address gets the new domain, the part before the @ stays as written, and you download the file with every change listed.
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
Five example rows with the change acme-old.com to acme.com get 2 addresses changed; the subdomain address changes only when subdomains are on.
- Addresses changed
- 2
- Rows
- 5
- Now repeated
- 0
What this means for you
A swapped domain is an address you expect, not a mailbox that exists; a check shows which addresses exist.
- Several changes at once
- Subdomains optional
- Local part kept as written
- Repeats counted
- Domain
- CSV
- Rebrand
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
Changed the domains? Check the new addresses before the send.
- Download the file, or use the check button under the result, which carries its addresses across.
- 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 change the domain of every email address in a CSV?
- Upload the file as a CSV or .xlsx, or paste the cells with the header row first.
- Pick the email column and write each domain change on its own line, old domain, arrow, new domain.
- Decide whether subdomains such as mail.old-company.com change too.
- Check the list of changed addresses and download the file.
Example
- You enter
- Five rows with an Email column holding ava.stone@acme-old.com, Ben@mail.acme-old.com, cara@globex.de, dev@ACME-OLD.com and eli@acme.com, with the change acme-old.com -> acme.com and subdomains left unchanged.
- You get
- 2 addresses changed: ava.stone@acme.com and dev@acme.com. 3 left as they were, including Ben@mail.acme-old.com, which changes to Ben@mail.acme.com when subdomains are turned on.
- Limits
- Runs in your browser; nothing is uploaded. It rewrites text and cannot tell whether the new mailbox exists.
When does a domain change need a whole-list swap?
A company that rebrands, merges or moves from .co to .com often moves its mailboxes to the new domain and keeps the names. A list written before that date still holds the old domains. Swapping the domain across the list turns jane@old-company.com into jane@new-company.com in one pass.
Use it only when you know the mailbox names carried over. If the new company changed its address format, such as first.last to flast, a swap writes addresses that do not exist.
How are the old domains matched?
A domain matches when the whole text after the @ equals the old domain, in any mix of capitals. old-company.com matches OLD-Company.com but not not-old-company.com. With subdomains on, mail.old-company.com also matches and becomes mail.new-company.com. When two lines could both apply, the exact match wins, then the longest parent domain.
The part before the @ is copied exactly, so Jane.Smith@Old-Company.com becomes Jane.Smith@new-company.com.
What does it not do?
It rewrites text. It does not check that the new mailbox exists, and it cannot know that two people shared one address. After a swap, run the file through a duplicate email remover, because two old addresses can become one. To find leads whose company moved without being told, use the company domain change checker.
Who uses this tool, and for what?
- Sales teams
- Update a prospect list after a target company rebranded.
- Admins
- Rewrite a contact export after your own company moved to a new domain.
- Cold emailers
- Fix a list that still holds a retired domain before checking it.
What can’t this tool tell you?
- It rewrites text and cannot tell whether the new mailbox exists.
- It assumes the part before the @ stayed the same after the move.
- Two old addresses can become one; the tool counts these but does not remove them.
- Only the first sheet of a workbook is read.
Common questions
- Can I change several domains at once?
- Yes. Write one line per domain, such as old-a.com -> new.com and old-b.com -> new.com. Two old domains may point to the same new one.
- Does it change the part before the @?
- No. It is copied exactly as written, capitals included. Only the domain changes, and it is written in lower case.
- What happens to addresses on other domains?
- They are left exactly as they were and counted as left alone. Cells that are not addresses, such as a blank or a note, are counted too.
- What if two rows end up with the same address?
- They are counted as now repeated, and the preview note tells you to run a duplicate remover. The tool does not drop rows itself.
- Will the new addresses work?
- Not necessarily. A swap writes the address you expect. Only a mailbox check shows whether it exists, and the check button under the result sends the new addresses to the verifier.
- Is my file uploaded?
- No. The file is read in your browser and goes nowhere.
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.