Arnt Gulbrandsen wrote:
In 2822 that address is apparently valid. Should that be so?
FWIW, "" is not allowed as <id-left> in I-D.ietf-usefor-usefor-12
and in an I-D about news URIs based on that approved USEFOR RFC.
It's still allowed in the 2822upd-00 I-D, that draft doesn't yet
support "canonical Message-IDs" as specified in the USEFOR RFC.
An interesting note in 2822 and 2822upd-00 is the "semantical
content" of a quoted-string, it's (no surprise) an empty string
I'm unsure what a <local-part> that's "semantically empty" might
be, apparently (quote) "it is simply interpreted on the particular
host as a name of a particular mailbox" (unquote 3.4.1).
And SMTP can transport it, so that appears to be fine, ignoring
the question of canonical Message-IDs for the moment. Better
than "\e2J"@example.org for e = ESC, or other NO-WS-CTL cases ;-)