Outlook’s font settings are located in the HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Common\MailSettings key. One way to do what you want is to configure a desktop user with the settings you want, then either export that key as a .reg file or use the Office Profile Wizard to capture and distribute the settings. (Complete details in the ORK). By manipulating the OPW's .ini file, you can get as granular as you want in terms of what settings you want to capture.
(Also, from my latest book

The registry value that controls the default stationery for the user is in the following registry value:
Key: HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Common\MailSettings
Value name: NewStationery
Value type: REG_EXPAND_SZ
Value: Name of the HTML file, without the .htm tag
For example, if the name of the stationery file is “Company Letterhead.htm,†the value for NewStationery would be “Company Letterhead.â€
Similarly, a value called NewTheme controls the default theme for messages created using WordMail.
You can also enforce a mandatory stationery file by creating a NewStationery value in the HKEY_CURRENT_USER\Software\Policies\Microsoft\Office\11.0\Common\MailSettings key. You can even create that value and leave it blank as part of a strategy to prevent the user from using any HTML stationery at all.
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Sue Mosher, Outlook MVP
Author of Configuring Microsoft Outlook 2003
and Microsoft Outlook Programming - Jumpstart for
Administrators, Power Users, and Developers