fetchmail POP error

Running Fetchmail under Mandriva 2006, it can't download mail from my ISP.
The logs show that it is sending RCPT TO: laidlaws@localhost That is not of
course my allotted e-mail address, and is not accepted by the mail server.
An error 450 results.

I can't work out where the "@localhost" is coming from. My machine is not
even called localhost. The login is my full email address, and that is
sent, but the "RCPT TO:" line is causing the problem. This doesn't seem to
be covered in the documentation. According to the fetchmail FAQ, I should
correct it in sendmail's config, but I am using postfix, which doesn't have
a distinct sendmail.conf. A HOWTO told me to configure postfix with my
email address as the FROM: address for root, but that was also the TO:
address, and my ISP got all the emails to root.

Any help would be appreciated.

Doug.