This worked for me. I have tested it on Outlook 2010 and Outlook 2016. Both 32-bit version.
These are the registry keys for 32-bit Office:
Windows Registry Editor Version 5.00
;Outlook 2007
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\12.0\Outlook\Forms\TrustedFormScriptList]
"IPM.Note.EnterpriseVault.Shortcut"=""
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\12.0\Outlook\Security]
"DisableCustomFormItemScript"=dword:00000000
;Outlook 2010
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\14.0\Outlook\Forms\TrustedFormScriptList]
"IPM.Note.EnterpriseVault.Shortcut"=""
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\14.0\Outlook\Security]
"DisableCustomFormItemScript"=dword:00000000
;Outlook 2013
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\15.0\Outlook\Forms\TrustedFormScriptList]
"IPM.Note.EnterpriseVault.Shortcut"=""
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\15.0\Outlook\Security]
"DisableCustomFormItemScript"=dword:00000000
;Outlook 2016
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\16.0\Outlook\Forms\TrustedFormScriptList]
"IPM.Note.EnterpriseVault.Shortcut"=""
[HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Microsoft\Office\16.0\Outlook\Security]
"DisableCustomFormItemScript"=dword:00000000