BeforeCheckNames Event
Occurs just before Microsoft Outlook starts resolving names in the recipient collection for an item.
Sub object_BeforeCheckNames(Cancel As Boolean)
object An expression that evaluates to an object in the Applies To list. In VBScript, use the word Item.
Cancel Optional (not used in VBScript). False when the event occurs. If the event procedure sets this argument to True, the operation is cancelled and the names in the recipients collection are not resolved.
Remarks
In VBScript, if you set the return value of this function to False, the operation is cancelled and the names in the recipients collection are not resolved.
Example
This VBScript example asks the user if the user wants to resolve names and returns False to cancel the operation if the user answers no.
Function Item_BeforeCheckNames()
If MsgBox ("Do you want to resolve names now?",4) = 7 Then
Item_BeforeCheckNames = False
End If
End Function