Occurs when Microsoft Outlook is starting, but after all add-in programs have been loaded. This event is not available in Microsoft Visual Basic Scripting Edition (VBScript).
Sub object_Startup()
object An expression that evaluates to an Application object.
Remarks
An Outlook Visual Basic for Applications (VBA) macro can use this event procedure to initialize itself when Outlook starts.
Example
This Microsoft Outlook Visual Basic for Applications example displays a welcome message to the user and maximizes the Outlook explorer window when Outlook starts.
Private Sub Application_Startup()
MsgBox "Welcome, " & Application.GetNamespace("MAPI").CurrentUser
Application.ActiveExplorer.WindowState = olMaximized
End Sub