Outlook VBA Script for saving Send Mail to different folders

At present, one of the teams at my company are using a script to allow them to save send mails to suppliers in a folder structure (just allows them to pick the folder each time any mail is sent out), I had a request that we set up a shared mailbox for them to keep all these corresponds in, and they would like to keep using the script to allow them to save into the new shared location. But of cause the script doesn't like going outside the default mailbox. Is there a easy solution to this. Script they using at present is below.

Private Sub Application_ItemSend(ByVal Item As Object, _
    Cancel As Boolean)
  Dim objNS As NameSpace
  Dim objFolder As MAPIFolder
  Set objNS = Application.GetNamespace("MAPI")
  Set objFolder = objNS.PickFolder
  If TypeName(objFolder) <> "Nothing" And _ 
     IsInDefaultStore(objFolder) Then
      Set Item.SaveSentMessageFolder = objFolder
  End If
  Set objFolder = Nothing
  Set objNS = Nothing
End Sub

Public Function IsInDefaultStore(objOL As Object) As Boolean
  Dim objApp As Outlook.Application
  Dim objNS As Outlook.NameSpace
  Dim objInbox As Outlook.MAPIFolder
  On Error Resume Next
  Set objApp = CreateObject("Outlook.Application")
  Set objNS = objApp.GetNamespace("MAPI")
  Set objInbox = objNS.GetDefaultFolder(olFolderInbox)
  Select Case objOL.Class
    Case olFolder
      If objOL.StoreID = objInbox.StoreID Then
        IsInDefaultStore = True
      End If
    Case olAppointment, olContact, olDistributionList, _
         olJournal, olMail, olNote, olPost, olTask
      If objOL.Parent.StoreID = objInbox.StoreID Then
        IsInDefaultStore = True
      End If
    Case Else
      MsgBox "This function isn't designed to work " & _
             "with " & TypeName(objOL) & _
             " items and will return False.", _
             , "IsInDefaultStore"
  End Select
  Set objApp = Nothing
  Set objNS = Nothing
  Set objInbox = Nothing
End Function