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

Question

I'm specifically looking for the minimum length of the prefix and domain.

I've seen conflicting information and nothing that looks authoritative.

For reference, I found this page which claims that a one character email address is functional:

http://www.cjvandyk.com/blog/Lists/Posts/Post.aspx?ID=176

I tried validating email addresses at Gmail and they expect prefix greater than or equal to 6.

These are obviously way off.

My web framework expects prefix greater than or equal to 2.

Answer 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.

Answer 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 x@y.zz is the shortest email possible (e.g. google's G.CN for china would result in the shortest email adress possible, e.g. i@g.cn, 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.

Answer 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.

Answer 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.