[fetchmail]Fetchmail and Courier

Can anyone help me with the .fetchmailrc file using courier?
I try to receive my ISP pop mail using fetchmail. Running fetchmail it shows 
the number of messages correct and tries to download them. But when 
fetchmail tries to send the mail to the local user, I get the error:
Can't even send mail to localuser... 

Does anybody know where that error comes from? 

Major Nono