Macro not working after outlook restart - vba

Question

I have a code which checks subject and email for a specific string and notifies users with YES/NO option.
When I restart outlook, I need to manually run MACRO to make it work.
I tried below code but I still need to run it manually.
Public WithEvents PasswordCheck As Outlook.Application
Public Sub Initialize_handler()
Set PasswordCheck = Outlook.Application
End Sub
Private Sub PasswordCheck_ItemSend(ByVal Item As Object, Cancel As Boolean)
Dim strBody As String
Dim strSubject As String
strSubject = Item.Subject
strBody = Item.Body
UCasePasswd = UCase("Test_123")
prompt = "Are you sure you want to send this email? It contains Password: "
If InStr(1, UCase(strSubject), UCasePasswd) > 0 Or _
InStr(1, UCase(strBody), UCasePasswd) > 0 Then
If MsgBox(prompt, vbYesNo + vbQuestion, "Check for Subject") = vbNo Then
Cancel = True
End If
End If
End Sub
Private Sub PasswordCheck_Startup()
Initialize_handler
End Sub

Answer 1

Change your procedure name
Private Sub PasswordCheck_ItemSend(ByVal Item As Object, Cancel As Boolean)
should be
Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
and be stored in the ThisOutlookSession module.
You should also place Option Explicit at the top of your module and declare UCasePasswd and prompt as string variables.
After testing this code worked without need to call it with the Application_Startup() routine as it's a built in event.
Also, I don't think you can re-reference Application_Startup as PasswordCheck_Startup the same way I've never seen Private Sub Workbook_Open() changed to anything else in Excel.
Edit:
This code in ThisOutlookSession worked perfectly - it's the only code in the module.
Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
Dim strBody As String
Dim strSubject As String
Dim UCasePasswd As String
Dim prompt As String
strSubject = Item.Subject
strBody = Item.Body
UCasePasswd = "TEST_123" 'Rather than use UCASE, just write it in upper case.
prompt = "Are you sure you want to send this email? It contains Password: "
If InStr(UCase(strSubject), UCasePasswd) > 0 Or InStr(UCase(strBody), UCasePasswd) > 0 Then
If MsgBox(prompt, vbYesNo + vbQuestion, "Check for Subject") = vbNo Then
Cancel = True
End If
End If
End Sub