Kmail won't work with satellite provider....

[Charlie <ariestao@clearmail.com.au>]

Have just subscribed to this list and using Icedove to post.
Using Debian Etch/Lenny
Have just been connected to satellite internet provider Clearnet who
have some Linux capable techs on their staff, but have not been able to
resolve a problem with Kmail 1.9.5 [using KDE 3.5.7] in Debian testing.

If I attempt to send an email to myself, the test of the satellite
provider [smtp], or anyone else using Kmail 1.9.5 [using KDE 3.5.7],
with the new email address after setting the accounts up, I get an error
message:-

Sending failed:
Message sending failed since the following recipients were rejected by
the server:
madesecure@clearmail.com.au (The server responded: "relaying mail to
clearmail.com.au is not allowed")
The message will stay in the 'outbox' folder until you either fix the
problem (e.g. a broken address) or remove the message from the 'outbox'
folder.

I have no problem sending through the old dialup provider and have used
Kmail for years. This is a new twist.

Am wondering if someone might point me in the direction of a fix?

Thanks in advance,
Charlie