John Levine wrote:
Technically it would not be hard to add a per-mailbox DNS lookup to SMTP,
ignoring the detail that no two mail systems agree what a mailbox is.
FYI, according to a non-standard rfc881:
Mailbox Support
The design of the domain servers provides two levels of support
for mail.
The first, called "agent binding", is that the right hand part of
the typical mail box (Y in X@Y) can be mapped a host that will
either accept the mail as the destination or accept the mail for
forwarding.
The second, called "mailbox binding", is to map the entire mailbox
(X@Y) to a destination (this mechanism can also support some
mailing list functions).
Masataka Ohta
