<atext> seems to be an undefined rule in RFC 5321.
Its undefinition is unchanged from 2821.
This is being noticed in a couple of different fora, so it's worth
resolving/fixing.
The definition in 5322, which is the same as 2822, seems appropriate.
Since it took ten years for anyone to notice this error, I agree it
would be nice to fix it, eventually, but not urgently. I would be
happy to file an erratum along these lines:
Section 4.1.2 refers to the ABNF symbol atext, but does not define it.
The intended definition is the same as in RFC 5322. Hence Section
4.1.2 currently says:
Atom = 1*atext
but it should say:
Atom = 1*atext
atext = ALPHA / DIGIT / ; Printable US-ASCII
"!" / "#" / ; characters not including
"$" / "%" / ; specials. Used for atoms.
"&" / "'" /
"*" / "+" /
"-" / "/" /
"=" / "?" /
"^" / "_" /
"`" / "{" /
"|" / "}" /
"~"
R's,
John