Andrew Gierth wrote:
[adding ietf-822 back in as this is getting into their territory]
2822 did specifically make the message-id syntax more restrictive than
822 (822 allowed whitespace in quoted strings, 2822 only allows it in
quoted-pair (i.e. preceeded by \)
If you look carefully, you'll see that not only must the whitespace
be backslash-escaped, that in turn must be within a quoted-string.
I.e.
<foo bar(_at_)baz(_dot_)com> illegal
<foo\ bar(_at_)baz(_dot_)com> illegal
<"foo bar"@baz.com> illegal
<"foo\ bar"@baz.com> legal
Message-ids that are valid under 2822 but not valid under 1036 (or are
longer than the 250-char limit) seem not to occur in mail with any
frequency (at least I don't see any in those mail collections I have
searched). I would be interested in whether anyone with access to large
amounts of real-world email can confirm this.
I have a small collection (22937 messages). I checked the msg-ids in
top-level header fields Message-ID, Received, In-Reply-To, References,
Resent-Message-ID, Content-ID, and Supersedes. There were none that
were simultaneously
1. legal under RFC 2822 generate rules
and
2a. longer than 250 octets including angle brackets
or
2b. had backslash-escaped space or control characters in a quoted string.
Those were all fairly recent messages (within the past 9 months).
Errors that were present included:
1. no @ (the ones in Received fields were generated by MS
"Internet Mail Service", by something called "ZMailer"
and/or "ZMailer Server", and by whatever is running at
maillennium.att.com, mtiwmhc11.worldnet.att.net,
mtiwmhc12.worldnet.att.net, and mtiwmhc13.worldnet.att.net.
Also apparently generated in Message-ID fields by
MDaemon.v2.7.SP4.R (in spam).
2. whitespace (sometimes on the left, sometimes on the right, in
both in one case), usually space characters, but in some cases
tabs (often these appear in References fields, where the
original Message-ID was compliant)
3. line folding (typically the result of some software mangling
a msg-id with internal whitespace)
4. 8-bit cruft (1 case; spam) generated either by Microsoft
MimeOLE V6.00.2600.0000 or by Microsoft SMTPSVC