Adding +something before the @ in a Gmail address gives you an address that still reaches your inbox: mail to name+shop@gmail.com lands in name@gmail.com. Gmail simply ignores the plus sign and everything after it when deciding where to deliver, while keeping the tagged form intact in the message headers so you can see which version was used. That makes it genuinely useful for one thing — finding out which site handed your address on — and close to useless for the thing most people hope it does, which is hiding your real address. Removing +shop takes one second and anybody can do it.
That gap between what the trick does and what people expect from it is where all the disappointment lives. Below is what is actually happening, the cases where it earns its place, and the five specific ways it fails.
What plus addressing actually does
The formal name for this is subaddressing: a local part (the bit before the @) split into the real mailbox name and a detail tag, separated by an agreed character. The plus sign is the conventional separator, and it has always been a legal character in an email address — forms that reject it are wrong about the rules, not protecting you from anything.
Delivery works because the mail server strips the tag before matching the mailbox. Nothing is created when you invent a tag. There is no list of your plus addresses anywhere, no setting to review, no limit on how many you use, and no step to take in advance. The first time a message arrives for name+newsletter@gmail.com is the first time that address has existed, and it works instantly.
Gmail is the best-known implementation but not the only one. Fastmail, Proton Mail, Outlook.com and iCloud all handle plus tags, though the details differ, so an address that works on one provider is not a guarantee for another. If you are relying on it anywhere other than Gmail, send yourself a test message to a tagged address first rather than assuming.
The dot trick is a different thing entirely
The other Gmail quirk people pair with this: for @gmail.com addresses, dots in the username are ignored, so n.a.m.e@gmail.com and name@gmail.com are the same mailbox. This is documented Gmail behaviour, not a loophole.
It is worth knowing for the opposite reason to plus addressing, though. Plus tags are something you choose to use; dot-insensitivity is something that happens to you. It means a stranger who mistypes your address with a dot in it still reaches you, and that mail intended for someone whose address differs from yours only by punctuation will arrive in your inbox — a recurring source of confused signup confirmations for people with short Gmail names. And because the dotted forms are invisible in the headers, you cannot use them to trace anything. Note also that on a Google Workspace account with a custom domain, dot handling depends on how that domain is configured, so do not assume gmail.com behaviour carries over.
Where it genuinely earns its place
Finding out who leaked your address
This is the real benefit and it is a good one. Use a distinct tag for each service, and the day spam starts arriving at name+hardware-store@gmail.com you know exactly which company's list it came from, whether through a breach, a sale or a careless partner. Without tagging, that is unanswerable. With tagging, it is visible in the To line. It is the cheapest available evidence for the question behind a sudden rise in spam.
Routing and filtering before you read anything
Because the tag survives in the headers, filters can act on it. One rule per tag will label, archive or file mail from a given service without touching anything else, and it keeps working even when that company rebrands or changes sending domain — which is what breaks filters built on the sender address instead.
No setup, no account, no cost
Every alternative involves either a subscription, a domain you own, or a second service to manage. Plus addressing involves typing four extra characters. For low-stakes labelling, that ratio is hard to beat.
Where it fails
1. Anyone can strip the tag
Your real address is sitting right there in the tagged one. A spammer who buys a list of plus addresses, or a script that normalises addresses before deduplicating them, removes everything between the plus and the @ and gets your base mailbox. Plenty of marketing platforms do this routinely as a housekeeping step, with no bad intent at all. So plus addressing is a label, not a mask: it tells you where a leak came from, and does nothing to limit where the leaked address goes next. If what you wanted was for the site never to learn your actual address, this is the wrong tool, and no amount of inventive tagging changes that.
2. A lot of forms reject the plus sign
Validation written from a half-remembered idea of what an email address looks like frequently refuses plus signs, and you meet this most often on exactly the sites where the tag would be most useful: airline bookings, banks, insurers, government portals, older retail checkouts. The error message rarely says what is wrong, so you waste time re-typing before realising the plus is the problem.
3. Worse, some accept it and break later
The nastier version is a form that accepts the tagged address at signup and then mishandles it afterwards. A login screen with stricter validation than the signup screen locks you out of your own account. A payment processor refuses the address at checkout. A support agent reading it over the phone drops the tag and cannot find your record. Password resets fire to an address their own system now considers invalid. You discover all of this later, when you need the account to work.
4. You cannot switch a tag off
There is no way to retire name+shop@gmail.com, because it was never created in the first place. Once a tag is being spammed, mail to it keeps arriving for as long as the mailbox exists, and your only remedy is a filter — which runs after delivery, meaning the mail is in your account regardless. A real alias can be deleted at its source so the mail stops at the server. A plus tag cannot.
5. Replies give the game away
When you reply, your mail client sends from your base address unless you have deliberately configured otherwise, and Gmail does not let you add your own plus-variant as a send-as identity. So the first time you answer a tagged message, the recipient sees the untagged address. For labelling that is irrelevant. For anything you were hoping to keep separate, it is the whole game.
Picking the right tool for what you actually wanted
If the goal is organisation — know which service mail came from, file it automatically, catch the leakers — plus addressing is a good fit and costs nothing. Use it for newsletters, shopping accounts and anything where the company already knows who you are.
If the goal is separation — the site should never hold your main address at all — you need an address that does not contain your real one. That means either genuine aliases, which forward to you from an unrelated-looking address and can be deleted individually, or a catch-all on a domain you own; the trade-offs between those are the subject of our comparison of aliases and disposable addresses, and the mechanics of the catch-all approach are in what a catch-all address does.
And if you are signing up for something you expect to use once — a forum post, a gated download, a trial of a tool you will probably abandon — none of that machinery is warranted. A temporary inbox reads the confirmation and then stops existing, so there is nothing to filter later and nothing to retire.
A rule that keeps it out of trouble
Use plus addressing where losing the tag would be an inconvenience, never where losing it would be a problem. Tag the newsletters and the shops. Do not tag the bank, the airline, the tax portal, or anything you will one day have to recover over the phone. That single distinction avoids almost every way this trick goes wrong, while keeping the one thing it is genuinely good at.