Matthias Andree:
> Am 04.01.2017 um 12:47 schrieb Wietse Venema:
> >
> > You need to make smtp(8) talk to a TCP port (or UNIX-domain port),
> > an arrange for a little daemon that listens on that port, and that
> > invokes ssh when a connection is established to that port. Then
> > the little daemon shuttles bits up and down. Such an on-demand
> > TCP relay could be done in Perl, Python, or any capable language.
>
> Thanks. The TCP relay and asynchronous or triggered start (even through
> autossh) is exactly what I'm considering brittle and am trying to avoid;
> I am looking for something synchronous. Looks like we still don't have
> that without someone extending the smtp client's source code.
Sorry, I fail to see the problem with using a synchronous SMTP proxy
service that manages the synchronous connection for you. Such a
synchronous service could even synchronously respond with 4xx when
a connection is unavailable.
Wietse
