mail's configuration (iphone 5)

Hi !

I've bought a new iPhone5, but I cannot configurate any mail account.

After filling out all fields (name, email address, passwrd etc), the system write me "Yahoo! Server Unavailable. Please try again later".

The same thing happens when I try to configurate my gmail account.

Please, help me to resolve this problem.

Thank you in advance,

Irina