RFC 5322, "Internet Message Format", October 2008Source of RFC: IETF - NON WORKING GROUP
Area Assignment: app
Errata ID: 2620
Reported By: Dominic Sayers
Date Reported: 2010-11-10
Rejected by: Pete Resnick
Date Rejected: 2011-05-16
Section 3.4.1 says:
Comments and folding white space SHOULD NOT be used around the "@" in the addr-spec.
It should say:
Comments and folding white space SHOULD NOT be used around the "@" in the addr-spec. Comments and folding white space at the beginning and end of an addr-spec are semantically invisible.
Section 3.2.2 says
"Runs of FWS, comment, or CFWS that occur between lexical tokens in a
structured header field are semantically interpreted as a single
but a leading or trailing space on an addr-spec would prevent it being interpreted as a valid RFC 5321 Mailbox (see http://tools.ietf.org/html/rfc5321#section-4.1.2).
This is important because this section of RFC 5322 also says
"It is therefore
incumbent upon implementations to conform to the syntax of
addresses for the context in which they are used."
Either the leading and trailing CFWS should be semantically "invisible" or additional logic is required for implementations to transform an RFC 5322 addr-spec into an RFC 5321 Mailbox.
Note: It may be true that leading and trailing CFWS is not "between lexical tokens". If so then it should be made clear what semantic interpretation to put on it in this case.
1. "addr-spec" does not appear in 5321. 5321 and 5322 have two different definitions for "Mailbox" and "mailbox" respectively, and that is a topic for an update of these documents, not for an erratum.
2. This report does not want the CFWS to be *semantically* invisible; it wants it to be *syntactically* invisible when moving an addr-spec from a 5322 context to a 5321 context. This document does not discuss this use.