Through the generous web coding skills of several COG members, most notably David Mamanakis, the following links show you how to configure several of the most popular email programs to send messages as plain text, which is the prefered method for posts to the cog listserver, and many others as well.

Outlook Express
These instructions are for version 5 of the free mailer Microsoft includes with IE, and should apply to most versions of Outlook and Outlook Express.

Eudora Pro 4.0
These instructions are for Eudora Pro from Qualcomm, and should help configure Eudora Lite (their free version) also.