What is the actual minimum length of an email address as defined by the IETF?

Solution 1:

The shortest valid email address may consist of only two parts: name and domain.

name@domain

Since both the name and domain may have the length of 1 character, the minimal total length resolves to 3 characters.

Solution 2:

well the problem is really the question.. email depends on if it is sent over the internet, or within a closed system (eg intranet). over the internet, I believe [email protected] is the shortest email possible (e.g. google's G.CN for china would result in the shortest email adress possible, e.g. [email protected], which is 6 characters long). on the intranet however, it is an entirely different thing, and i@y would be possible, which is just 3 characters long.

Solution 3:

I believe the standard you are looking for is RFC 2822 - Internet Message Format

More specific info on email address restrictions in RFC 3696 - Section 3

To quote the spec:

Contemporary email addresses consist of a "local part" separated from a "domain part" (a fully-qualified domain name) by an at-sign ("@").

So three characters is the shortest.

I originally got this info from Phil Haack's blog post.

Solution 4:

Many mail-servers will not accept the email-address if there aren't at least 2 characters before the @. That doesn't make it an invalid address, but if the servers don't know that, it sure can lead to a lot of problems.