The IMAP administers the receiving and viewing of messages and SMTP(Simple Mail Transfer Protocol) administers the sending of outbound messages. When you setup IMAP, you will also be needed to setup SMTP. Yahoo also supports POP(Post Office Protocol) that is an email standards sponsored by governing the receipt of messages. POP(Post Office Protocol) retrieves a message from the server, then delete it from here, So it's available only the device onto which it was downloaded.
It's quite easy Yahoo Email Settings to setup in manually with the help of this article. Just visit and configure yourself it - http://emailscrunch.populr.me/what-is-the-imap-and-smtp-server-for-yahoo-mail
