[expert] Mail Bouncing Wantonly

[Brian Hartman]

Hi, all.

I've got e-mail I'm trying to send, but it keeps getting bounced back from a 
specific address.  The error message I'm getting is:

nvalid final delivery userid: xxx@localhost

Has anyone heard of this error?  I'm assuming the problem's on my end, since 
I'm prettty sure the person at the other end (using a Windows box) isn't 
"localhost".  I'm trying to send via Kmail.  Any suggestions?