# Plus addressing

Plus addressing is the convention by which mia+promo@ delivers to the same mailbox as mia@; the part after the plus is a tag the owner chooses, reported as is_alias and stripped in normalized_email.

Date: 2026-09-13

Plus addressing, also called sub-addressing, is the convention most mailbox providers follow of delivering `mia+anything@acme.com` to the mailbox of `mia@acme.com`: the part after the plus sign is a tag the owner chooses per signup, useful for filtering and for seeing who leaked an address, and invisible to the mailbox itself. Gmail adds a second rule of its own, ignoring dots in the username, so `m.i.a@gmail.com` and `mia@gmail.com` are one inbox too.

## What Spaw answers

`is_alias` reports a plus-tag, and `normalized_email` carries the canonical inbox with the tag removed and Gmail's dots folded away. Dedupe a list, key a suppression entry and count a repeat on `normalized_email`, never on the raw input, or one person becomes many. The `alias` weight is 5: a tag is a hint that a signup bonus is being farmed, not a fault.

## What it does not mean

A tagged address is a real address, and the mailbox is verified like any other. The tag is the owner's, and a form that rejects it loses a careful customer rather than a fraudster.

Reference: https://spaw.co/glossary/plus-addressing