unicode - Are email addresses allowed to contain non-alphanumeric characters?

Question

I'm building a website using Django. The website could have a significant number of users from non-English speaking countries.

I just want to know if there are any technical restrictions on what types of characters an email address could contain.

Are email addresses only allowed to contain English letters, numbers, _, @ and .?

Are they allowed to contain non-English alphabets like é or ü?

Are they allowed to contain Chinese or Japanese or other Unicode characters?

Answer 1

Email address consists of two parts local before @ and domain that goes after.

Rules to these parts are different:

For local part you can use ASCII:

• Latin letters A - Z a - z
• digits 0 - 9
• special characters !#$%&'*+-/=?^_`{|}~
• dot ., that it is not first or last, and not in sequence
• space and "(),:;<>@[] characters are allowed with restrictions (they are only allowed inside a quoted string, a backslash or double-quote must be preceded by a backslash)

Plus since 2012 you can use international characters above U+007F, encoded as UTF-8.

Domain part is more restricted:

• Latin letters A - Z a - z
• digits 0 - 9
• hyphen -, that is not first or last, multiple hyphens in sequence are allowed.

Regex to validate

^(([^<>()[].,;:s@"]+(.[^<>()[].,;:s@"]+)*)|(".+"))@(([^<>()[].,;:s@"]+.)+[^<>()[].,;:s@"]{2,})

Hope this saves you some time.