After the third question this week from administrators who migrated to Outlook 2010 or 2013, only to discover their custom forms are not working as expected, I thought I should mention this. In most cases the forms will likely work just fine in Outlook 2010 or 2013, however, if the forms contain scripting and are published to a public or shared folder, scripting will need to be enabled.
One admin writes:
We have a custom contacts form with some vbs code in it supporting a command button and checking for required categories. I am hoping someone can help explain some odd behavior we are seeing. The code in the custom form works fine if you 'Choose form' from the developer tab, populate the contact data, and save. However, once saved, if you open the contact, you can make changes to the data, but none of the code functions anymore. Going to design view of the broken contact and selecting 'Run this form', again, runs everything fine.
These symptoms definitely point to the scripting setting. You can check the setting for All script in shared folders and Allow script in Public folders in File, Options, Trust Center, Email Security.
These settings can be controlled using Group Policy. In the Outlook admin template, look under Outlook Options, Advanced.