Sub GetValueUsingRegEx()
    Dim olMail As Outlook.MailItem
    Dim Reg1 As RegExp
    Dim M1 As MatchCollection
    Dim M As Match
     
    Set olMail = Application.ActiveExplorer().Selection(1)
    
    Set Reg1 = New RegExp

    With Reg1
        .pattern = "(\d{12})"
        .Global = True
    End With
    If Reg1.Test(olMail.Body) Then
        Prompt$ = "Unmasked order id info found on email! Do you want to proceed on sending your email?"
        If MsgBox(Prompt$, vbYesNo + vbQuestion + vbMsgBoxSetForeground, "Order Id Info Found!") = vbNo Then
        End If
    End If
    
End Sub

Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
   Call GetValueUsingRegEx
End Sub