Follow the mentioned steps to successfully connect your inbox. 

Go to Yahoo mail. 

Click Account Info.

Go to Security. 

Generate App password. 

Use App generated password as a password while connecting your inbox.

SMTP Configuration:

SMTP Address: smtp.mail.yahoo.com

SMTP Port: 465

Password: App-generated password

IMAP Configuration:

SMTP Address: imap.mail.yahoo.com

SMTP Port: 993

Password: App-generated password

Enable: TLS