Based on the logic provided so far, send the mail if @Result <> ''
You could use the following parameter in your email:
@query =
'SELECT ''Process Name: '' + CONVERT(VARCHAR(25),Process_Name ,0)
+''Last Message Time: ''+ CONVERT(VARCHAR(25),Last_Message_Time,0)
FROM [ITF3].[dbo].[Process]
WHERE Process_ID IN (1,2,3,4)
AND Last_Message_Time >DATEADD(HOUR,-168,GETDATE())
ORDER BY Last_Message_Time DESC'
Don't set @attach_query_result_as_file to 1.