Nowadays Yahoo has released one new security feature in order to strength the communication against 3rd party app, such as email client. This is what happened when i was trying to configure the outlook client. It thrown an error keep saying i put wrong credential which i believe not. After gone thru quick research i found we need to setup 3rd party application password prior we can connect to Yahoo mail.
You can find account info on top right corner your account once logged in and choose security account.
Choose manage application password and select appropriate platform as you wish to configure.
Let’s say you will configure Outlook client in IOS, then you may select Outlook IOS. Press apply and you will find 16 character that you can put on your email client.