Anybody aware of SMTP AUTH tunnel software?

I'm probably not the only one who has run into this situation. The SMTP
server through which I want to send my outgoing mail uses SMTP AUTH to
authenticate sending rights.

While it's possible to set up sendmail and postfix to use SMTP with TLS and
AUTH I would rather use a tunnel approach to handle these layers, allowing
any plain SMTP compliant software to reach the mail server that needs
authentication.

Is anyone aware of such an SMTP AUTH tunnel program? If none exists, I
might write one over the holidays since I already have written the required
code in my JBMail software.

The way this could work is as follows. Your SMTP-compliant software
(whatever it may be) could connect to localhost:1234, reaching the tunnel
program. The tunnel would then establish a connection to
mail.example.com:25 and transfer all SMTP communications verbatim, except
that it would insert the AUTH command to authenticate to the remote server.
The tunnel therefore needs to do very little; other then the AUTH command,
all other data lines are transmitted unmodified.

--
Jem Berkes
http://www.sysdesign.ca/

Jem Berkes wrote:
> I'm probably not the only one who has run into this situation. The SMTP
> server through which I want to send my outgoing mail uses SMTP AUTH to
> authenticate sending rights.
>
> While it's possible to set up sendmail and postfix to use SMTP with TLS and
> AUTH I would rather use a tunnel approach to handle these layers, allowing
> any plain SMTP compliant software to reach the mail server that needs
> authentication.
>
> Is anyone aware of such an SMTP AUTH tunnel program? If none exists, I
> might write one over the holidays since I already have written the required
> code in my JBMail software.
>
> The way this could work is as follows. Your SMTP-compliant software
> (whatever it may be) could connect to localhost:1234, reaching the tunnel
> program. The tunnel would then establish a connection to
> mail.example.com:25 and transfer all SMTP communications verbatim, except
> that it would insert the AUTH command to authenticate to the remote server.
> The tunnel therefore needs to do very little; other then the AUTH command,
> all other data lines are transmitted unmodified.

Either I don't get what you need, or you're making this more complicated
than it needs to be. If you have box A that needs to do an SMTP AUTH to
box B in order to send mail out, why can't you just run a mail server on
box A which relays all outgoing mail to box B using SMTP AUTH, then
allow all necessary clients to relay through box A? At a minimum a
client should either be able to invoke sendmail on box A locally, or
connect to port 25 on box A, in order to send its payload. Writing a
tunnel program to do this would be like reinventing the wheel, except
that your wheel is in the shape of a sphere instead of a circle.

-Don

>

> Either I don't get what you need, or you're making this more
> complicated than it needs to be. If you have box A that needs to do an
> SMTP AUTH to box B in order to send mail out, why can't you just run a
> mail server on box A which relays all outgoing mail to box B using
> SMTP AUTH

The main reason is because I want to also allow other kinds of SMTP clients
(not just one mail server) to send through the server that requires SMTP
AUTH. How else can you get a client that doesn't support AUTH to send?

--
Jem Berkes
http://www.sysdesign.ca/