This morning at TechEd Microsoft announced Visual Studio Tools for Office 2005 would support creating managed add-ins for Microsoft Outlook. Srinath Vasireddy has more details and links to the download and preliminary documentation over on his blog.
This is a great announcement for Outlook because previously creating managed add-ins was a rather complicated procedure. You had to deal with creating a COM shim in C++ or work around it by having mscoree.dll act as a shim for your add-in. Now with the VSTO tools the default template takes care of all of that for you. Another great benefit of using the VSTO to develop managed add-ins for Outlook is that AppDomains are isolated across add-ins so there isn’t a huge potential for conflicts anymore. The VSTO code also implements the common work around for the Outlook shutdown problem, which means you won’t need to duplicate this effort in your own code.
One of the only things to watch out for when deploying VSTO add-ins is that the add-in has to be registered in CAS with trust permissions to allow it to execute. For a locked down environment using the Outlook Security Form and Exchange, you’ll have to register the add-in loader in the security form as well to get it trusted. The only thing to watch out for here is that by trusted the add-in loader, you implicitly trust all managed add-ins that use the add-in loader, which is where the CAS trust permissions come into play.
I’m very excited about the VSTO tools and I know they are going to make it so much easier for Outlook solutions to be developed in managed code without the huge overhead that was previously required.