What Does the + Sign Do in an Email Address?

The plus sign (+) in an email address separates your base username from a tag. The tag is ignored during delivery, so all mail arrives in the same inbox. This technique is defined in RFC 5233 and is called subaddressing or plus addressing.

Plus Addressing SyntaxAll deliver to the same inbox
[email protected]            ← Your real address
[email protected]   ← Tag: "shopping"
[email protected]    ← Tag: "netflix"
[email protected]   ← Tag: date

Is the Plus Sign Valid in Email Addresses?

Yes. The plus sign is a valid character in the local part (before the @) of an email address according to RFC 5321 and RFC 5322. However, some websites use broken validation that rejects the + character. In those cases, use the dot trick instead.

Site Compatibility
Some websites incorrectly reject email addresses with a + sign. If a signup form rejects your plus address, use a dot trick variation instead.

How to Use It for Gmail Filtering

  1. Sign up for a service using [email protected]
  2. Open Gmail Settings → Filters and Blocked Addresses
  3. Create a filter: To: [email protected]
  4. Apply a label, skip inbox, or star automatically

Tracking Who Sells Your Data

Use a unique alias per service (e.g., [email protected], [email protected]). If you receive spam addressed to [email protected] from a sender that is not the New York Times, you know exactly who leaked your data.

Which Providers Support Plus Addressing?

Try the Free Gmail Alias Generator

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