I've seen people list email addresses at Gmail with "+" within the recipient name.

Here's an example of what I mean:

[email protected]

That said, if you attempted to create a Gmail account with "+" recipient name, you would get this error message:

Please use only letters (a-z), numbers, and periods.

Is the "+" simply read and removed by the mail server, and if so, is this specific to Gmail, or is it universal to all email addresses/servers? Meaning my guess is that people to this for readability, but I've always been puzzled by it, since it appears to not be possible to create an Gmail account using a "+".

  • 1
    "sub-addressing" and some other providers allow for - (minus) instead Apr 26, 2012 at 1:17
  • Here is a technique I use to filter certain notes to myself to appropriate labels using "plus addressing".
    – ale
    Jul 27, 2012 at 12:59
  • Is it possible to have an address for sub or nested labels? May 2, 2015 at 8:45

4 Answers 4


Plus sign is GMail's delimiter for aliases, which many people use for filtering and tracking spam.

For example, you want to make sure that your bank's emails are all legitimate so you'll register your email with the bank as [email protected] and then create a filter that deletes all emails that don't match from:MyBank AND to:[email protected]. Alternatively, when you register with a shady site you can provide your email as [email protected] and then create a filter to delete everything that is sent to that address.

However, beware that some sites have poorly-written validators on allowed addresses, which block emails with plus sign, which is actually an allowed character per RFC 5322. Google doesn't allow it simply because it's a reserved character in their system.

  • plushaters has a rant about sites with poorly-written validators, with links to better validators. "plussed addresses" work the same with lots of other email providers.
    – David Cary
    Apr 26, 2012 at 18:09
  • @dbbrv, is this the only feature in GMAIL or other service providers also gives this option ?
    – SAM
    Mar 2, 2017 at 7:26
  • @SAM: using +tag for filing is an old and widespread convention. See the "Author's address" in ietf.org/rfc/rfc5321.txt
    – LarsH
    Jan 25, 2018 at 18:10

The plus sign is not simply a Gmail feature, but one of the valid characters in email addresses as specified by RFC-5233:


It's true that many email validation tools don't take this into account. RFC3696 details techniques on how to properly validate email addresses:


Of note is that the following characters are valid as long as they are not used to begin or end the local part of the address:

! # $ % & ' * + - / = ?  ^ _ ` . { | } ~
  • 3
    I think only the dot cannot be used for the beggining and end of the local part. Otherwise the others are allowed. From RFC3696: Without quotes, local-parts may consist of any combination of alphabetic characters, digits, or any of the special characters ! # $ % & ' * + - / = ? ^ _ ` . { | } ~ period (".") may also appear, but may not be used to start or end the local part, nor may two or more consecutive periods appear. Stated differently, any ASCII graphic (printing) character other than the at-sign ("@"), backslash, double quote, comma, or square brackets may appear without quoting.
    – oxygen
    Mar 17, 2013 at 12:40

Google allows the user to use the plus sign and the period to make variations on their address

  • The plus sign allows to to add any words you like after your base address
  • the period lets you divide your name up anyway you want.

These are great for filtering your emails.

You are right that you can't have plus sign in your base address.


Adding the + sign to an email address is simply a variation of the same email address, just like the . in Gmail accounts.

The reason why people may use the + sign in their email address with Gmail is to filter their emails. In Gmail, you can filter emails based on who they're sent to, not just who they're sent from. Keeping this in mind, some people utilize this feature to prevent spam, or to better sort their inbox.

Source: I use Gmail, but there's also a help article on Google's website explaining this

  • But this depends on the email server you are using. So the first sentence isn't a universal truth.
    – Wolf
    Feb 25, 2021 at 13:16

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