Quick answer: If an email address is in A2, use =IFERROR(LOWER(REGEXEXTRACT(TRIM(A2),"^[^@\s]+@([^@\s]+)$")),"REVIEW") to extract its domain. For example, hello@example.com becomes example.com. This extracts text; it does not verify whether an address can receive mail.
Practical example & checks
A small email-domain test set with expected outputs
Put the input in column A and the formula below in B2. This extracts text; it does not validate deliverability or company ownership.
=IFERROR(LOWER(REGEXEXTRACT(TRIM(A2),"^[^@\s]+@([^@\s]+)$")),"REVIEW")| Input | Expected result |
|---|---|
| hello@example.com | example.com |
| TEAM@Example.ORG | example.org |
| Alex <alex@example.com> | REVIEW |
| missing-at.example.com | REVIEW |
| user@sub.example.com | sub.example.com |
Copy the formula down and check the five outputs. A subdomain remains a subdomain; the formula does not determine the registrable company domain. It also is not a complete email-address validator. Use REVIEW as a queue for manual inspection, not evidence that a mailbox definitely does not exist.
Original ThinkQuarry teaching material added 19 October 2026. Hypothetical examples are not product-test results.
Domains are useful for grouping a contact list by organization, counting how many addresses share a provider, and checking obvious mismatches between emails and website records. Keeping the original address alongside the extracted domain makes those checks easier to review.
Set up three columns
Use A for Original email, B for Extracted domain, and C for Review note. Leave A untouched. That matters when an imported field contains a display name, stray punctuation or multiple addresses. If you edit away those clues immediately, you lose the context needed to correct the record.
| Input in A | Expected output in B | Meaning |
|---|---|---|
| hello@example.com | example.com | Domain extracted |
| SALES@EXAMPLE.ORG | example.org | Outer spaces removed, domain lowercased |
| name.example.com | REVIEW | No separating @ |
| first@example.com;second@example.org | REVIEW | More than one address |
Understand the formula
TRIM removes ordinary extra spacing around the input. REGEXEXTRACT looks for one nonempty part before @ and captures the part after it. The anchors require the pattern to cover the whole cell, rather than grabbing a domain from the middle of messy text. LOWER standardizes the result. IFERROR sends failed matches to REVIEW instead of leaving an error in the column.
This conservative pattern is intended for ordinary address lists. It is not a complete implementation of every legal email-address format. A REVIEW result means a person should inspect the input, not that the address is necessarily invalid.
Apply it to a list
- Paste the formula into B2.
- Confirm the output for a known address before filling down.
- Copy the formula through the populated rows only.
- Filter B for REVIEW and inspect those cells.
- When your list is approved, copy B and paste values into a separate export copy if the receiving system expects plain text.
For a bounded batch, an array version can fill the results automatically:
=ARRAYFORMULA(IF(A2:A500="","",IFERROR(LOWER(REGEXEXTRACT(TRIM(A2:A500),"^[^@\s]+@([^@\s]+)$")),"REVIEW")))Keep the cells below the array formula empty so the results have room to expand. Adjust 500 to fit the working batch. In locales that use semicolon separators, change commas between arguments, not characters inside the quoted pattern.
Do not confuse domain matching with identity
An address at gmail.com tells you its provider, not the owner’s company website. A business may also use a separate email domain, a subdomain, or an outside support platform. Flag mismatches for review instead of automatically moving addresses between rows.
For example, a row containing example.com and help@example.org deserves a source check. The different domain is a useful clue, but it is not enough evidence to change the data. Look at the company’s current contact page or the source where the email was collected.
Common mistakes
Removing subdomains blindly: support@mail.example.com produces mail.example.com. Converting that to a registrable domain requires rules beyond “take the last two pieces,” especially for endings such as co.uk.
Calling extraction verification: A correctly shaped address may still be nonexistent, abandoned or catch-all. Keep a separate column for any actual delivery or verification result.
Overwriting the original: If you later need the full address for a contact import, the domain alone cannot reconstruct it.
Common questions
Can I extract the name before @ too?
Yes, but it is an account name, not reliable evidence of a person’s actual name. Keep it as a technical field rather than treating it as a verified contact identity.
Why does the formula return REVIEW for a display name?
A value such as Alex <alex@example.com> contains more than a plain address. Clean that field deliberately on a copy before applying the plain-address formula.
Next, use our duplicate-review workflow to identify repeated addresses without losing newer records.
Sources and further reading
Prepared by ThinkQuarry. Documentation checked 3 October 2026. Menu labels may vary by version. Featured image: original AI-generated photographic concept created for ThinkQuarry. This editorial visual is not a product screenshot.
