It has to be of the syntactic form of an <addr>. The usual implication of
such syntax appearing in a standard is that a thing that looks like an
<addr> is expected to be an <addr>. If there is any other intent (e.g. it
was a Message-ID), then one would expect the standard to say so.
The local part is not a mailbox, and it's not a Message-ID. If it
were a mailbox, it would say it was a mailbox, or if it were a
Message-ID, it would say it's a Message-ID. We're not deconstructing
the Talmud here, the words mean what they say.
The wording in 4871 strongly suggests, by implication, that the
domain at least is supposed to be a domain.
Um, it's not an implication, its a MUST:
The domain part of the address MUST be the same as or a subdomain of
the value of the "d=" tag.
R's,
John
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