asp.net - How to add namespace in aspx file?

Question

i have added C# code in aspx file, but it is showing error

The type or namespace name 'Mail' does not exist in the class or namespace 'System.Net' (are you missing an assembly reference?)

How i can add nampespace to aspx file i have tried <%@ import namespace="Westwind.Tools"%> but it does not work?

Answer 1

<%@ Import Namespace="System.Net.Mail" %>