[plug] Domains blocking mail from dialup pools

[James Devenish]

In message <418AD86B.3040106 at tigris.org>
on Fri, Nov 05, 2004 at 09:33:31AM +0800, Timothy White wrote:
> Maybe I will just have to set up a tunnel, any one known how I can set
> up a tunnel using SSH so that the connection appears to come from the
> computer I tunnel into.

Shouldn't be a problem -- it's generally the default no-frills behaviour
anyway.

> I don't which computer I will use yet but it may have [its] own SMTP
> server

Normally, an SMTP MTA would attempt to deliver 'directly' to the
recipient's MX, but you should be able to find a configuration option
that enables you to specify a 'relay host' through which outgoing mail
will be sent. You should find that you are able to specify a 'port
number' for the relay host.

> My Computer:25 --> Static computer:5678 which is connected to mail.com:25

I would suggest:

localhost:5678 -> relayhost:25 -> mail.com:25

For example, if we were to use a simplistic OpenSSH tunnel, you could
do:

mycomputer% ssh -N -L 5678:localhost:25 relayhost

You would then, on mycomputer, set the relay host to be localhost:5678.
Thus, your MTA will deliver all outgoing e-mail to localhost:5678 and
SSH would tunnel it to relayhost:25 (using the SSH port), where it would
be placed into the queue as normal. Relayhost need not be reconfigured
in any way to support this, provided that it already allows relaying for
mycomputer.