Can I Use an Underscore ( _ ) in an Email Address?

Underscore in an Email Address?

Have you noticed underscore characters in email addresses? Wondering whether they are okay to use, and how you can add them to your email address? Find here all you need to know about using the underscore ( _ ) in an email address.

First, Shake Your Coconuts

Like many a food that comes in a wrapper, coconuts go bad (faster) when the container is broken, and bacteria or fungi find their way inside.

Most coconuts do not have obvious holes or gaping creeks, of course, but they still may be compromised with minuscule cracks. Through these, the pests get in—and, importantly, the coconut’s water seeps out.

So, shake coconuts to judge their freshness and whether they are intact. If you hear and feel lots of heavy fluid sloshing around inside, the coconut is likely a good pick.

Now, want to introduce a crack in your email address without making it go bad? Try this in place of a whitespace character:

Can I Use an Underscore ( _ ) in an Email Address?


The underscore character (_, ASCII code 95) is a valid character anywhere in an email address’s username.

You can

  • start an email address with an underscore,
    Example: is valid.
  • end your email address’s username part with an underscore and
    Example: is valid.
  • use multiple underscore characters in your email address.
    Example: is valid.

Not all underscores are alike: The above applies to the ASCII underscore character ‘_’. It is not true for other characters that resemble it or other methods of underlining; see below.

Underscore in Email Address: FAQ

Can I use alternative underscore characters?


Characters that look like an underscore but are not the ASCII underscore (ASCII 95, Unicode U+005F) are not allowed in email addresses.


The following characters will not work as underscores in email addresses:

Unicode NameUnicode CodepointDisplay
Combining low lineU+0332̲
Combining macron belowU+0331̱
Fullwidth low lineU+FF3F_

Can an underscore character be part of the domain name?


Domains and host names cannot contain underscores. The hyphen is the only not alphanumeric character allowed in RFC 1035 (Domain Names – Implementation and Specification).

(Can I use underscore in an email address first published April 2020, last updated February 2024)

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