origins of Bracketed Quad notation

[David L. Nicol]

Can anyone point me to the IETF RFC describing e-mail addresses
of the form david@[10.10.10.10]   Although web pages refer to
this construction as a "821-compliant address" I found no discussion
of referring to hosts by anything other than names within 821.













--
        "Lord Macbeth knew he was approaching the SITE of the rout
 from the SIGHT of odd body parts scattered on the blasted heath."