VSTO - Customize Outlook: Reading pane,
Navigation pane and windows in C#,VB.NET

Add-in Express™
for Microsoft® Office and VSTO

Outlook is a featured application for Add-in Express

For the majority of VSTO developers Outlook remains the most popular target application for their add-ins. It stands to reason because Microsoft Outlook is the main business application from the Microsoft Office family. Sticking to the trends, Add-in Express for VSTO offers to Outlook developers some advanced features that may be of great use in customizing Outlook and building powerful plug-ins. Among them:

  • Advanced Outlook View and Form Regions that allow customization of Outlook windows (Explorer, Inspector, Reading pane, To-Do bar) with your .NET forms and controls.
  • Separate support of two types of Outlook windows: Explorer and Inspector windows.
  • Outlook context-sensitivity binds toolbars and ribbons to certain Outlook windows, folders or context.
  • Option and property pages embed .NET forms into the main Options and Folder Properties dialogs.
  • Navigation pane shortcuts add your own set of shortcuts to the Navigation Pane.
  • Outlook-specific events of the ADXModule make Outlook development more comfortable than using PIA-based event helpers.

Advanced Outlook View and Form Regions

The main feature provided by Add-in Express and loved by many Outlook developers is called Advanced Outlook View and Form Regions. It enables you to embed any .NET forms practically into all Outlook windows:

Advanced form regions: a sample user interface of an Outlook add-in.

The main Outlook window on the picture has three additional panes, My Links, Alerts and Sales Report, that are typical .NET forms embedded by Add-in Express using Advanced Outlook Regions. Now Add-in Express supports embedding .NET forms into the following Outlook windows and panes and allows you to:

  • Replace the content of the main Outlook window (Outlook Explorer) with your form (an analog of the home page of Outlook folders)
  • Embed one or several forms at the top, bottom, right and left of the Outlook view pane.
  • Use your .NET forms on the Reading pane.
  • Place your custom form onto the To-Do bar, Navigation pane and Outlook bar.
  • Embed your form around the content of any Inspector windows such as mail windows, task forms, appointments, journal items, contact forms, etc.

On the following page your can find all types of Advanced Outlook Regions.

Explorer and Inspector toolbars and ribbons

Add-in Express distinguishes between two main types of Outlook windows, Explorer and Inspector, giving to your disposal separate toolbar components. Each of them is developed taking into consideration all habits of behavior of the appropriate Outlook window, as well as navigation and synchronization between them. Keep in mind that with these components you don't need to track context and constant reconnects when switching between Outlook windows. Every time you refer to your toolbars you can be sure they exist in the current active context whether it is the current active Explorer or one of several opened Inspectors.

As for the Ribbon UI on the Outlook 2007 and Outloo 2010 Inspector window, Add-in Express for VSTO supports customizing Outlook ribbons for all contexts and ribbons published by Outlook 2007 and 2010, namely:




  • TabSetSmartArtTools
  • TabSetChartTools
  • TabSetPictureTools
  • TabSetDrawingToolsClassic
  • TabSetWordArtTools
  • TabSetDiagramTools
  • TabSetOrganizationChartTools
  • TabSetTextBoxTools
  • TabSetTableTools
  • TabSetEquationTools
  • TabSetPictureToolsClassic
  • TabSetInkTools

Please note, you don't code ribbons and context, you specify them via the corresponding properties of Add-in Express components. See also the Explorer and Inspector toolbars HowTo page.

Outlook context-sensitivity

Another great feature provided by Add-in Express for customizing Outlook is the possibility to bind custom toolbars or toolbar controls to certain Outlook folders. Each Outlook-specific component publishes special properties that bind the component (a toolbar or a toolbar control) to the folders specified by their names or by their content. The picture below shows that a toolbar will be shown for all mail and task folders. Please note, in the same manner you can organize different sets of controls on one toolbar or different sets of toolbars for different Outlook folders. It doesn't require any coding, simply use the appropriate properties of toolbar and control components.

The main Options dialog and folder property pages

With Add-in Express for VSTO you can add your custom tabs to the main Options dialog of Outlook as well as to the Properties dialog of the certain folders. It doesn't require any coding either. You can create a form for the option page basing on the Add-in Express template (available through the Add New Item dialog of the add-in project) and select the form in the corresponding property of the ADXModule as shown in the picture below. See also Option pages and folder property pages components.

Navigation Pane shortcuts

Add-in Express includes a special component that you can use to customize the Outlook Navigation Pane with your own groups of shortcuts. The component provides a visual designer for shortcut groups and shortcuts and makes all work with shortcuts easy and no-coding. More about Navigation pane customization.

Outlook-specific events and event helpers

Finally, the ADXModule publishes a lot of Outlook-specific events that are available without manual creating of event sinks and helpers.

The list below contains all Outlook events that are directly available from the ADXModule.

Outlook Application events

  • AdvancedSearchComplete
  • AdvancedSearchStopped
  • AttachmentContextMenuDisplay
  • BeforeFolderSharingDialog
  • BeforeOptionPageAdd
  • ContextMenuClose
  • FolderContextMenuDisplay
  • ItemContextMenuDisplay
  • ItemLoad
  • ItemSend
  • MAPILogonComplete
  • NewMail
  • NewMailEx
  • OfficeColorSchemeChanged
  • OptionPagesAdd
  • Quit
  • Reminder
  • ShortcutContextMenuDisplay
  • Startup
  • StoreContextMenuDisplay
  • ViewContextMenuDisplay

Outlook Explorer events

  • ExplorerActivate
  • ExplorerAddCommandBars
  • ExplorerFolderSwitch
  • ExplorerBeforeItemCopy
  • ExplorerBeforeItemCut
  • ExplorerBeforeItemPaste
  • ExplorerBeforeMaximize
  • ExplorerBeforeMinimize
  • ExplorerBeforeMove
  • ExplorerBeforeSize
  • ExplorerBeforeViewSwitch
  • ExplorerSelectionChange
  • ExplorerViewSwitch
  • NewExplorer

Outlook Inspector events

  • InspectorActivate
  • InspectorAddCommandBars
  • InspectorBeforeMaximize
  • InspectorBeforeMinimize
  • InspectorBeforeMove
  • InspectorBeforeSize
  • InspectorClose
  • InspectorDeactivate
  • PageChange
  • NewInspector