OUTBOX: No Supported Way to Deploy Outlook VBA Projects
...I added a new category to the blog, you will see it is called OUTBOX. As a support engineer I send out a lot of mail that could be useful to everyone. You shouldn't have to open a support case just to get this information. So here I'll provide some email excerpts that I think might be helpful...
The issue you’re experiencing is that you are having trouble deploying a VBA macro for Outlook. As we discussed on the phone, there is no supported method for deploying VBA projects. The best way to create a deployable addition to Outlook is by developing a COM AddIn. Fortunately, the COM AddIns are implemented in a similar fashion to the VBA code used in Outlook macros. In most cases this is a simple copy and paste with very few modifications.
Here are some of the MSDN links that explain VBA deployment issues and COM AddIns in more detail:
229911 OL2000: Managing and Distributing Outlook VBA Projects
"IMPORTANT: Although you can do this, Microsoft Product Support Services cannot support deploying solutions in this way."
290780 OL2002: Code Does Not Work After You Distribute a VBA Project
316983 OL: A Sample COM Add-in That Uses the Visual Basic 6.0 Add-in Template
291163 How to create a COM Add-in for Outlook 2002
Some of these articles make reference to specific versions of Outlook but they are all relevant to Outlook 2003 as well.
...Many customers call in on this issue. It is usually a pretty easy case to solve because COM Addin code and VBA code are nearly identical. However, this could be avoided with a little developer education, so I'm just trying to get the word out...