I think defining an
UNAUTHENTICATE/LOGOUT/whatever-you-want-to-call-it extension would be
a great idea, but it's definitely a separate effort from any of this
I understand what it would do, but I'm not sure I understand what
problem it solves.
Send on behalf schemes are the main target audience here. Given the
concentration of email recipients on over-the-top providers and the larger
ISPs, being able to unauthenticate and reauthenticate without having to get a
new connection to some very busy systems going can result in significant
savings in latency.
If you want to drop your auth credentials, you
can always quit and call back. Yes, that's slower, but does it
happen often enough to merit asking people to add yet another hack
to their mail servers?
On some systems yes, it does.
Ned