Postfix From Field
 

Every time I send a message from my Fedora Core 3/POSTFIX box, localhost.cottsay.net appears in the from field instead of just cottsay.net.
The $myorigin setting is set to $mydomain, but it doesn't make a difference. I had it working correctly before, but forgot to backup my postfix config file before I wiped it. I think it was an alias or relay setting or something. Any ideas?