Can I use ASP or C# code to create a web page from where can enter user id and password and access my yahoo mailbox?[/al_question]
Sure. Since it’s just software, anything is possible. But if I understand what you’re asking for it would be a lot of work. To my knowledge there is no API to Yahoo mail. This article might also help: Can I read web mail using a pop3 mail reader? – mentioned therein are some tools that somehow are doing the same kinds of things you would need to do.