RFC 5322, "Internet Message Format", October 2008Source of RFC: IETF - NON WORKING GROUP
Area Assignment: app
Errata ID: 3135
Status: Held for Document Update
Publication Format(s) : TEXT
Reported By: Ashley Willis
Date Reported: 2012-02-25
Held for Document Update by: Barry Leiba
Date Held: 2019-11-13
Section 3.2.4 says:
quoted-string = [CFWS] DQUOTE *([FWS] qcontent) [FWS] DQUOTE [CFWS]
It should say:
quoted-string = [CFWS] DQUOTE ((1*([FWS] qcontent) [FWS]) / FWS) DQUOTE [CFWS]
The text following this definition states that a "quoted-string is identical to atom, semantically." "Semantically, neither the optional CFWS outside of the quote characters nor the quote characters themselves are part of the quoted-string; the quoted-string is what is contained between the two quote characters."
The published definition allows, for example, an angle-addr of <""@ietf.org> which is equivalent to <@ietf.org>, hence invalid. The corrected definition ensures that at a minimum there is one FWS or qcontent between each DQUOTE.
Currently allowed yet invalid: <""@ietf.org>, <foo.""@ietf.org>, <"".firstname.lastname@example.org>, and <foo."".email@example.com>.
As a quoted-string must be bound by the ends of the local-part or by a dot, there is no change in regard to the currently invalid addresses such as <foo""@ietf.org>, <""firstname.lastname@example.org>, and <foo""email@example.com>.