Certs won't work, according to ms. From
http://msdn.microsoft.com/library/de.../odc_dsvba.asp

"It should be noted that the security model for Microsoft Outlook 2002
differs from other Office XP applications. In addition to a user's security
settings, described in Table 1, Outlook 2002 VBA macro projects
(****regardless of whether they are digitally signed or not****) are
subjected to the restrictions on certain Outlook 2002 object model property
and method calls imposed by the Outlook E-mail Security Update that is an
integral component of Outlook 2002. There is no way to bypass these
restrictions except if a Microsoft Exchange Server administrator uses the
Default Security Settings (Admin.oft) template to lower the Outlook security
settings. However, this is not recommended as it also has the side effect of
lowering overall security restrictions, including the ability to run viruses."