Yahoo! E-mail Settings for iPhone

Outgoing Mail Server Configuration

Server Hostname smtp.mail.yahoo.com
Server Port 465
Username The part before the @ sign of your e-mail address
Authentication Password
SSL/TLS Yes

Incoming (IMAP) Mail Server Configuration

Server Hostname imap.mail.yahoo.com
Server Port 993
Username The part before the @ sign of your e-mail address
Authentication Password
SSL/TLS Yes