🚀 go-pugleaf

In theory SMTP provides a facility that could be used the way you
describe, the TURN command.  To use it you'd call up the host you
wanted to prod, negotiate a TURN (at which point you turn into an SMTP
"server" instead of an SMTP "user"), then get instant gratification as
the foreign machine dumped all its mail out to you.

In practice I am not aware of any SMTP server that implements TURN
except to negotiate a close correctly after a foreign site has
inflicted a TURN on you.  Too much hair, particularly for mailsystems
where the smtp-server (mail listener) and smtp-user (mailer daemon)
are two different program.

There's also a potential for misuse by pinheads if something like TURN
were implemented.  For the case you mention it is pretty clearly
justified, but what do you do about the bozo who calls you up as a
regular habit because he thinks your retransmission queue scan time is
too slow?  Stop answering the phone, I guess....

--Rob Austein <SRA@XX.LCS.MIT.EDU>