http://office.microsoft.com/en-us/ork2003/CH011480831033.aspx
Code signing certificates cost a few hundred dollars a year. Here is a list of providers from Microsoft.
http://msdn.microsoft.com/en-us/library/ms995347.aspx
To self sign, use selfcert.exe. Run
C:\Program Files\Microsoft Office\OFFICExx\selfcert.exe
http://www.howto-outlook.com/howto/selfcert.htm
In the VB Editor go to Tools, Digital Signature and add the certificate to the project.
Get out of the VB Editor and Outlook and go back in. Outlook will ask if you want to always trust macros from this certificate. Say
yes.
Outlook macro project is here.
File: VbaProject.OTM
Folder: %appdata%\Microsoft\Outlook
Example: C:\Documents and Settings\username\Application Data\Microsoft\Outlook