Here are the email server settings that work for me on iMac or iPad using Mac Mail program.
Verizon changed to different email server.
Make sure password for account is correct by resetting password:
Reset password by clicking "I cannot access my account link" on page or login below
Enter username here to reset password : https://signin.verizon.com/sso/forgotflows
Passwords must match for verizon yahoo & verizon account.
email server settings:
Name: john smith
user name: john smith (Do not use full email address here)
Incoming Mail Server: incoming.yahoo.verizon.net
SSL: on (Port 995)
Outgoing Mail Server: outgoing.yahoo.verizon.net
SSL: on (Port 465)
Password: current password for account
Save all settings and check for new email. Good luck.