RFC Errata
RFC 5321, "Simple Mail Transfer Protocol", October 2008
Note: This RFC has been updated by RFC 7504
Source of RFC: IETF - NON WORKING GROUPArea Assignment: art
Errata ID: 5414
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: David Romerstein
Date Reported: 2018-06-29
Held for Document Update by: Barry Leiba
Date Held: 2019-11-13
Section 4.1.2 says:
Quoted-string = DQUOTE *QcontentSMTP DQUOTE
It should say:
Quoted-string = DQUOTE 1*QcontentSMTP DQUOTE
Notes:
As written, this allows for an email envelope recipient (Forward-path) with a NULL value for the local part of their address. This is a functional departure from similar wording in the preceding RFC 821, which defines quoted-string in such a way as to require at least one character that is not one of the surrounding quotation marks.