Three years ago (can’t believe it’s been so long) I blogged about creating an Outlook add-in. The add-in was developed with VSTO 2, but now I thought it was time to upgrade it to VSTO 3 and try out the ClickOnce deployment. If I was impressed about how easy and much better it had become to develop for Outlook 2007 with VSTO 2, I must say that the developing with VSTO 3 is a lot better. The biggest problem in VSTO 2 was deployment with many security problems but in VSTO 3 that is elegantly solved.

It is just as easy as doing a regular ClickOnce installation with a few minor limitations. Compared to doing a ClickOnce deployment with Windows Forms you can’t choose which files that should be included, but rather all locally copied references are included in the setup. This means that you probably will have to change that for a couple of your references because you have them in the GAC on your dev machine. On the web server you will have to set up a new MIME type for the .vsto file name extension. For a more detailed getting started guide you can read for example this on MSDN.

Another nice new feature is that it has become much easier to create new regions on the built-in forms. As I blogged about here you needed to design the form in Outlook, import it to the project and add registry settings to get it to load, but now all you have to do is create a special windows forms user control, called Outlook Form Region in the Add-dialog. This makes it a lot easier to create form regions and removes a lot of plumbing code. There is no longer needed to do any registry modifications, it rather just works.

References:
General Experience with Outlook 2007 Add-in Development
Adding a Property Page to Outlook 2007 Options Dialog
Form Regions in Outlook 2007 (Part 1)
Form Regions in Outlook 2007 (Part 2)
Custom Task Panes in Outlook 2007