configuring kmail

[stanhughes at sunflower.com]

I have just put kunbuntu on a new computer and am now trying to configure kmail

I have it receiving mail , but can't seem to configure it to send mail.  I have followed all the suggestions on the email servers site.
 
  The message I get is:
   Sending failed:
Authentication failed.
Most likely the password is wrong.
The server responded: "5.7.0 authentication failed"
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.
The following transport was used:
 Sunflower.com

  The password is not wrong, so any ideas what might be?

  Thanks,
       Stan Hughes