Is it possible to use double @ in an email address?

Question

I know Yahoo and Gmail do not accept it. But I want to know if it's possible for a person to create an email address with double @ in address and if they can receive emails with that address?

For example: info@stackoverflow.com@example.com.

I do not want to use this non standard format, but I want to know if a hacker can do it?

Lookup "email address" on wikipedia - it will point you at the right standards etc to get the definitive answer. — John3136, Oct 07 '15 at 08:04
I've given a comment lower but older people will remember having to nest Banyan vines email for gateways (Digital famously used Banyan Vines). It has to be in the local-part and it has to be quoted. "foo@example"@example.com is valid. Many servers filter anything that looks like it is wrapped in this way, sadly. — mckenzm, Apr 01 '22 at 17:45

score 4 · Answer 1 · edited Oct 31 '20 at 02:02

4

According to the wiki, it is allowed.

Space and special characters "(),:;<>@[\] are allowed with restrictions (they are only allowed inside a quoted string, as described in the paragraph below, and in addition, a backslash or double-quote must be preceded by a backslash).

edited Oct 31 '20 at 02:02

BSMP

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answered Sep 04 '19 at 05:42

rong bo

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score 3 · Answer 2 · edited Oct 07 '21 at 05:54

No it is not allowed. See the RFC Section 3.4.1

An addr-spec is a specific Internet identifier that contains a locally interpreted string followed by the at-sign character ("@", ASCII value 64) followed by an Internet domain. The locally interpreted string is either a quoted-string or a dot-atom. If the string can be represented as a dot-atom (that is, it contains no characters other than atext characters or "." surrounded by atext characters), then the dot-atom form SHOULD be used and the quoted- string form SHOULD NOT be used. Comments and folding white space SHOULD NOT be used around the "@" in the addr-spec.

It has to be quoted. "foo@@bar"@example.com is a valid email. Read further. — mckenzm, Apr 01 '22 at 17:36

score 2 · Accepted Answer · edited Jun 20 '20 at 09:12

As this question's answer says:

The local-part of the e-mail address may use any of these ASCII characters:

Uppercase and lowercase English letters (a-z, A-Z)

Digits 0 to 9

Characters ! # $ % & ' * + - / = ? ^ _ ` { | }

Character . (dot, period, full stop) provided that it is not the first or last character, and provided also that it does not appear two or more times consecutively.

so it is usually not allowed :)

Is it possible to use double @ in an email address?

3 Answers3