How to create Outlook form regions in C#, VB.NET
Outlook 2010, 2013 Replace All region
Add-in Express™ Regions
Outlook form regions based on Add-in Express
Outlook form regions are essentially sub-panes that can be docked in the window for any Outlook item (also known as an Inspector window) for both read and compose modes. All Outlook item types such as Mail, Task, Contact and Appointment are supported with Add-in Express Regions. Regions can be docked to any side of the Inspector window and will work equally well under Outlook 2013, 2010 and 2007 as well as with Outlook 2003.
Outlook form regions are implemented using the concepts detailed extensively on the Region concepts page. In summary, your form regions:
Finally, when the user closes Outlook, Add-in Express Regions stores the state, size and position for each region, and restores all settings for the next Outlook session.
Complete replacement for Outlook Inspector
With Add-in Express Regions you can completely replace all pages of any Outlook Inspector window. The standard Replace All Form Region types were introduced in Outlook 2007 and are also supported in Outlook 2010 and 2013, but are still not supported for Outlook 2003. Add-in Express Regions, however, do support Outlook 2003 as well as Outlook 2007, 2010 and 2013, and are very easy to implement. You can bind your replace all regions to specific folders, inspector types, message classes or inspector modes.
On-demand form regions
Even better, Add-in Express Regions provides a new kind of region: on-demand regions. This region type allows you to embed your forms under all pages of the Inspector window and the user can display them whenever they want to. Like all other regions based on Add-in Express, on-demand Outlook form regions can be bound to specific folders, inspector types, message classes or inspector modes.