In an earlier contribution to this discussion, Theo Markettos
wrote:
Steve Hayes wrote:
http://de.wikipedia.org/wiki/SMTPS (Google translation from German):

Originally, the Internet Assigned Numbers Authority in early 1997 to
port 465 had registered for SMTPS. [1] This was withdrawn in late
1998, specified as a STARTTLS was. [2] With STARTTLS same port can
be used without TLS, and TLS. [4] [5] For the SMTP was seen as
particularly important because clients respond with this protocol
also foreign server from which they can not know whether it is
providing a separate port for TLS. [3] The port 465 is now Source
Specific Multicast for audio and video recorded. [4] [5]

Funnily enough, that's what I eyeballed looking for port numbers but
didn't bother reading the German ;-)

It looks like my SMTP server is listening on 25, on which it sends an
SMTP greeting, and 465, to which the socket opens but nothing comes
back when I type in garbage, but nothing listening on 587. So the
client must be using 25 (I can only see by asking someone to read out
the config over the phone).

I can ask the server people to change the port to 26, so I'll give
that a try. Or maybe that's blocked too like 24? When I changed the
daemon listening on 24 to 443 (a good port for raw tunnels) it
connected, so they may be firewalling other 2x ports too.

Theo

There's some stuff about blocked ports on 3's site. Go to
http://www.three.co.uk/Help_Support/...Broadband_Help and type 'email'
in the search box - and follow the links about Port 25 etc.
--
Cheers,
Roger