close but no cigar
try like
Private Sub Application_ItemSend(ByVal item As Object, Cancel As Boolean)
Dim mi As MailItem, mybcc As Recipient, ob As Items
If item.Subject = mycriteria Then ' match some criteria to subject or other, so not all emails will open excel
Set ob = GetNamespace("mapi").GetDefaultFolder(olFolderOutbox).Items
Do While ob.Count > 0 ' wait till outbox is empty
DoEvents
Loop
Set xl = CreateObject("excel.application")
xl.Visible = True
'leave visible for user, or open appropriate workbook, what ever
End If
end sub