Does a mail program keep asking for your password?
If you have 2 step login verification enabled you will need to create an application password for programs that do not support the 2 step logins such as asking for a code sent to your phone.
To create an application password go to your Yahoo inbox, then click the Gear and select Account Info:
In the left side navigation click Account Security:
Scroll down to the App Passwords section, type in the name of the mail program, then click Generate password:
If you have 2 step login verification enabled you will need to create an application password for programs that do not support the 2 step logins such as asking for a code sent to your phone.
To create an application password go to your Yahoo inbox, then click the Gear and select Account Info:
In the left side navigation click Account Security:
Scroll down to the App Passwords section, type in the name of the mail program, then click Generate password: