setting smtp in Kmail

[Lisi Reisz]

I am having a problem with setting smtp on my granddaughter's Kubuntu 8.04.  I 
have tried both via Gmail's smtp server (she is using a Gmail address) and 
our ISP's smtp server.  

If I attempt to send I get:
<quote>
Sending failed:
Unknown host mailhost.zen.co.uk
</quote>

or
<quote>
Sending failed:
Unknown host smtp.googlemail.com
</quote>

I have checked and rechecked the settings and have compared teh Zen settings 
to mine, which works flawlessly.

What should I do next?

TIA
Lisi