vba - How can I automatically run a macro when an email is sent in Outlook?

Question

The script below works great but I have to manually run the Initialize_handler routine every time I open Outlook for it to work.

Public WithEvents myOlApp As Outlook.Application

Public Sub Initialize_handler()
Set myOlApp = CreateObject("Outlook.Application")
End Sub

Private Sub myOlApp_ItemSend(ByVal Item As Object, Cancel As Boolean)
Dim prompt As String
prompt = "Are you sure you want to send " & Item.Subject & "?"
If MsgBox(prompt, vbYesNo + vbQuestion, "Sample") = vbNo Then
    Cancel = True
    End If
End Sub

As far as I can see to make this work automatically I should be able to add the below script to ThisOutlookSession. However this doesn't work and I have no idea why.

My macro security is set properly and it is running the code on startup but for some reason it doesn't work until I manually open the VBA editor click into Initialize_handler and press F5.

Private Sub Application_Startup()
  Initialize_handler
End Sub

Answer 1

The convoluted method described here https://msdn.microsoft.com/en-us/library/office/ff865076.aspx indicates "The sample code must be placed in a class module".

I suggest you use the special class module ThisOutlookSession only. You could experiment with your own class module but if you just want this to work then replace all your code with this in ThisOutlookSession.

Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
Dim prompt As String
prompt = "Are you sure you want to send " & Item.Subject & "?"
If MsgBox(prompt, vbYesNo + vbQuestion, "Sample") = vbNo Then
    Cancel = True
    End If
End Sub