When installing on Citrix or Terminal Server the installer will present an additional option that is not available when installing on a regular workstation. This will allow you to install the addin in an inactive state.

Installer option "Install addin in active state&quo;

The corresponding registry entry would be:

[HKEY_LOCAL_MACHINE\Software\Lucatec\Mask]
"AddinActive"=dword:00000000

As a result, all users that should use the addin would have to explicitly enable it in their user profile first. This can be done via a simple checkbox in the addin's options (in Outlook: Tools->Options->Lucatec® Mask).

Addin active checkbox on addin's Options page

The corresponding registry entry for enabling the addin on a per-user basis would be:

[HKEY_CURRENT_USER\Software\Lucatec\Mask]
"AddinActive"=dword:00000001

However, doing it this way usually only makes sense when the unlicensed users are in the majority. In the reverse case it should be simpler to just install the addin in the default active state and then explicitly disable it for the users that shouldn't use it:

[HKEY_CURRENT_USER\Software\Lucatec\Mask]
"AddinActive"=dword:00000000

If you want to prevent your licensed users from accidentally disabling the addin you can set the following registry value to hide the corresponding checkbox from the user interface:

[HKEY_LOCAL_MACHINE\Software\Lucatec\Mask]
"ShowAddinActiveOptionRDP"=dword:00000000

Registry options for controlling addin state and user's ability to dis-/enable the addin themselves

A general note on how the addin handles registry entries: With very very few exceptions, all options can be set both under HKEY_CURRENT_USER and HKEY_LOCAL_MACHINE. The addin will first look at HKCU and if it doesn't find a value there it will look for the same value under HKLM. In other words: as long as there are no entries under HKCU the values under HKLM define the addin's default behaviour (these can be set via the installer) but as soon as values are set under HKCU these will override the settings at the machine level.