imap and pop3 info of a mail server

[eluser]Altaf Hussain[/eluser]
Hi,
I am developing an email client in codeigniter. I need some help to know the following.
1) How i can know the pop3 or imap server details of an email address for example example@yahoo.com or any other email ? Is there any method where i can do this programmatic in CI and the user only enter his email and all the imap or pop3 server info are taken automatically .

2) If a mail server like yahoo, did not provide free access to pop3 to fetch emails, then is there any other way to fetch all emails from such accounts?

I am searching for both from about two days, but got nothing.
Please help me if anyone know about these .

Thank you