Dear Diane,
See below my full coding; It is working, but i need to add one another folder too as mentioned before.
Thanks.
Sub Search_Related()
Dim myOlApp As New Outlook.Application
Dim oMail As Outlook.MailItem
Dim strFrom, strSubject As String
Dim txtSearch As String
Set oMail = GetCurrentItem()
strFrom = oMail.SenderName
strSubject = oMail.ConversationTopic
'Search crieria for the related mail search
txtSearch = "[Conversation]:=""" & strSubject & """ (to
" & strFrom & ") OR from
" & strFrom & "))"
'Search current folder & subfolders
myOlApp.ActiveExplorer.Search txtSearch, olSearchScopeSubfolders
Set myOlApp = Nothing
End Sub