Gmail dot and plus address normalizer: find repeat signups
Gmail ignores dots and anything after a plus sign, and googlemail.com is the same mailbox, so jane.doe@gmail.com, janedoe+trial2@gmail.com and J.A.N.E.DOE@googlemail.com reach one inbox. This tool adds each row's canonical Gmail address, groups rows that share an inbox and counts the repeats. It flags; it doesn't delete. Nothing leaves your browser.
Sample result
3 rows all reach one inbox, janedoe@gmail.com, so 2 are hidden repeats.
- Inbox
- janedoe@gmail.com
- Rows
- 3
- Distinct inboxes
- 1
What this means for you
Drop the repeats so one person isn't emailed three times or counted as three sign-ups.
- Drops Gmail dots and +tags
- googlemail.com counts as gmail.com
- Groups rows that reach the same inbox
- Optional +tag rule for other domains
- Gmail
- Dedupe
- CSV
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
How do I find repeat Gmail signups in a list?
- Paste addresses or upload a CSV export, such as signups or trial accounts. The email column is found automatically. Files can be up to 25 MB.
- Leave "ignore +tags on other domains" off unless you know your users' providers support plus addressing.
- Press Normalize and group. Each group shows the inbox and every spelling of it on your list.
- Download the CSV. Every original row is kept, with canonical_email, how many rows share that inbox, and whether the row is the first one seen.
Example
- You enter
- Three rows:
jane.doe@gmail.com,janedoe+trial2@gmail.comandJ.A.N.E.D.O.E@googlemail.com. - You get
- All 3 reach one inbox,
janedoe@gmail.com: the CSV keeps every row, adds canonical_email and same_inbox_rows (3), and marks only the first as first_seen, so 2 are hidden repeats. - Limits
- Runs in your browser with no row cap; an uploaded file can be up to 25 MB.
Do dots matter in Gmail addresses?
No. Google says dots don't matter in Gmail addresses, so janedoe@gmail.com and jane.doe@gmail.com are one account. Its plus addressing delivers jane+anything@gmail.com to jane@gmail.com. And messages sent to @gmail.com and @googlemail.com are the same. Capital letters never matter. Put together, one Gmail inbox can sign up for your product as many times as there are ways to place dots and tags.
This applies only to gmail.com and googlemail.com. On a Google Workspace company domain, dots do make a different address, so the tool never removes them there. Plus tags are different: Google Workspace, Microsoft 365, Fastmail and Proton all document them, so the option to ignore +tags on every domain is there for lists where that's safe.
What is the Gmail dot trick, and how do I catch it?
The Gmail dot trick is signing up many times with dotted or +tagged spellings of one Gmail address, since every spelling lands in the same inbox. To your database they look like different users; to Gmail they are one. Normalizing every address to its canonical form, then grouping, shows the repeats.
If the goal is a send list with each inbox once, remove duplicate emails does that, with the same Gmail matching as an option. This page is for the other job: understanding who signed up. A product team looking at trial abuse needs to see that 14 trial accounts are one person, which spellings they used and which came first, without losing the rows. So nothing is removed. The download adds the canonical address and a group count beside your data, ready to filter or join in a spreadsheet.
Normalizing doesn't catch every repeat. Someone can open a second Gmail account, use a disposable address or an Apple Hide My Email relay, and none of those share a canonical form. Our guide to plus addressing and trial abuse goes through what string rules can and can't catch.
How do I remove dots from a Gmail address at signup?
Lower-case the address, treat googlemail.com as gmail.com, drop everything from the first + in the local part, then remove the dots. Store that canonical form next to the address the user typed, and check it for an existing account at signup. Send email to the address they typed, not the canonical one, since some people rely on their +tag to filter your mail. Plus addressing is a general convention, described as subaddressing in RFC 5233, but dot-insensitivity is a Gmail rule only.
This page normalizes; it doesn't generate dot variations or aliases. To stop throwaway signups, pair normalization with blocking disposable emails at signup and a mailbox check, so the account is tied to an inbox that exists.
Is this better than a spreadsheet formula?
| This tool | Google Sheets formula | |
|---|---|---|
| Dots and +tags on gmail.com | Removed | Possible with nested functions |
| googlemail.com as gmail.com | Handled | Needs another SUBSTITUTE |
| Dots kept on company domains | Yes | Only if you add an IF on the domain |
| Groups and counts the repeats | Yes, with every spelling | Needs COUNTIF on a helper column |
For a Gmail row in Sheets: =SUBSTITUTE(REGEXREPLACE(LOWER(INDEX(SPLIT(A2,"@"),1)),"\+.*",""),".","")&"@gmail.com". Wrap it in an IF on the domain so other addresses are left alone.
Who uses this tool, and for what?
- SaaS teams
- Export trial or free-plan signups and see which accounts share one Gmail inbox through dots and +tags, with the first signup marked, before you decide on a limit per inbox.
- Marketers
- Find people who entered a giveaway or claimed a first-order discount several times with
jane.doe,janedoe+1andj.anedoespellings of one address. - Sales ops
- Merge CRM contacts whose Gmail addresses differ only by dots or googlemail.com, using the canonical_email column as the join key in your spreadsheet.
What can’t this tool tell you?
- Dots are removed only for gmail.com and googlemail.com. On Google Workspace and every other domain they are kept, because they make a different address there.
- It can't link separate accounts: a second Gmail address, a disposable inbox or an Apple Hide My Email relay won't share a canonical form.
- Stripping +tags on other domains is an opt-in guess. Some mail systems treat
+as a normal character. - It doesn't check the inbox exists. Normalizing is a string rule, not a mailbox check.
Common questions
- Do dots matter in Gmail addresses?
- No. Google says jane.doe@gmail.com and janedoe@gmail.com are the same account, with dots anywhere in the name. This is true only for gmail.com and googlemail.com; on a company domain using Google Workspace, a dot makes a different address.
- Can I use dots in my Gmail address?
- Yes. You can give out your address with or without dots, in any position, and mail still arrives. Gmail treats every version as the same username, so dots can't be used to create a separate account.
- What is a Gmail alias?
- Usually it means a plus address such as jane+shop@gmail.com, which Gmail delivers to jane@gmail.com. You don't need to set it up. Gmail can also send from other addresses you own, which Google also calls an alias.
- What is the canonical form of a Gmail address?
- Lower case, with gmail.com in place of googlemail.com, everything from the first + removed and every dot in the name removed. J.A.N.E.Doe+news@googlemail.com becomes janedoe@gmail.com.
- Is this a Gmail dot variations generator?
- No. It goes the other way: it takes many spellings and shows which inbox they all reach. That is what you need to spot repeat signups, not to create them.
- How is this different from removing duplicate emails?
- The duplicate remover deletes repeats to give you a clean send list. This tool keeps every row and adds the canonical address and a group count, so you can see that several signups are one person, which is what you need for trial abuse or account review.
- Should I strip +tags for every email domain?
- Only if your list is mostly on providers that support plus addressing, such as Google Workspace, Microsoft 365, Fastmail or Proton. Some mail systems treat + as an ordinary character, where jane+1@ and jane@ are different people. That's why the option is off by default.
- Does a normalized address mean the inbox exists?
- No. Normalizing shows when two spellings reach the same inbox, not whether that inbox is real or still open. A mailbox check answers that.
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? $9 one-time covers 2,500 emails, no subscription
One plan, 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.