Dear Log,
Discovery: changing the "Domain to add to unqualified addresses" setting in Eudora to something that's not a valid hostname will cause very very strange behavior. So I spent much of today trying to figure out why my ISP's SMTP host was refusing to play nice with my Eudora, instead screaming "503 POLITE PEOPLE SAY HELO FIRST!".
In a rare change of roles, the cat tried to help by mashing his fists on the keyboard and screaming, while I tried to make it all go away by sleeping.