Laptop email sending problem

[Steven Vollom]

I recently purchased a used Compaq Ivo N620c laptop.  I configured the 
email client the same as my desktop.  Both have Kubuntu 8.04 and KDE 
3.5.9.  Both run Firefox and Thunderbird as default.  When I attach my 
DSL cable moden to the laptop, I am able to surf the internet, as well 
as receive emails, however when I attempt to send an email, a window 
opens asking the password for my email server.  I type in the password 
an click enter and the selfsame window opens again and again.  I get an 
unable to connect to the server also.  I have tried to get help from 
att.yahoo, but they are not helpful because I am not using their mail 
program or their browser and am using Kubuntu Hardy instead of Microsoft 
or Apple.  I have used Kubuntu for 3 years with Firefox and Thunderbird 
on my desktop with no problems.  The fact that I receive emails but 
cannot send suggests that at least part of the program is working.  Help 
please.

Steven Vollom