Email headers: Allowed/disallowed characters in FROM header: (display) name

Question

I'm trying to find an answer to the question about which characters is allowed (or disallowed) in the FROM header (display) name..

"My Display Name" <[email protected]>

I'm talking about the My Display Name in quotations.

I've looked at tools.ietf.org/html/rfc822 and tools.ietf.org/html/rfc2822 but can't seem to find anything specifying these requirements. Perhaps because it accepts all unicode/UTF-8 characters but it doesn't state that either.

Any help or reference to some documentation would be greatly appreciated.

Answer 1

Email header fields, of which From is one, can only contain ASCII characters. See Section 3.1.1 of RFC 822. However, RFC 1342 gives a mechanism to work around this limitation.

Answer 2

Characters that have values between 33 and 126, inclusive, except colon.

So if your "customer" has this name "Clinic: X" this will be blocked by most email client providers. You can "replace the ":" with " " in that case for example.

See https://tools.ietf.org/html/rfc5322#section-2.2

According to Section 2.2 of RFC 5322 : "A field name MUST be composed of printable US-ASCII characters (i.e., characters that have values between 33 and 126, inclusive), except colon. A field body may be composed of printable US-ASCII characters as well as the space (SP, ASCII value 32) and horizontal tab (HTAB, ASCII value 9) characters (together known as the white space characters)