|Determine the "identity" of your emails. Set with SAM the sender and the folder folder for sent items with the help of rules.
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).
Private WithEvents m_Items As Outlook.Items
Private Sub Application_Startup()
Set m_Items = Application.Session.GetDefaultFolder(olFolderInbox).Items
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)
Prop.Value = Atts.Count