Display Number of Attachments

Paste the code to the ThisOutlookSession module, then restart Outlook. After the first email was received while the macro was running, you can add the new property 'NumberAttachments' to the folder view (View Settings/Columns).

  How to add macros to Outlook

Private WithEvents m_Items As Outlook.Items

Private Sub Application_Startup()
  Set m_Items = Application.Session.GetDefaultFolder(olFolderInbox).Items
End Sub

Private Sub m_Items_ItemAdd(ByVal Item As Object)
  Dim Atts As Outlook.Attachments
  Dim Props As Outlook.UserProperties
  Dim Prop As Outlook.UserProperty
  Dim PropName As String
  
  PropName = "NumberAttachments"
  
  Set Atts = Item.Attachments
  Set Props = Item.UserProperties
  Set Prop = Props.Find(PropName, True)
  If Prop Is Nothing Then
    Set Prop = Props.Add(PropName, olText, True)
  End If
  Prop.Value = Atts.Count
  Item.Save
End Sub