Verizon/Yahoo Mail Problems

I've looked everywhere for a similar problem to what I am experiencing, but can't find anyone who seems to be having the same thing going on. For more than a year, my family has used Verizon yahoo mail without any problems on the Apple Mail application. Nothing has changed recently, and the preferences settings have been:
POP Account
Email: myaddress@verizon.net
Incoming Server: incoming.yahoo.verizon.net
Outgoing server: outgoing.yahoo.verizon.net
Username: myaddress@verizon.net
Correct password
Outgoing mail server (SMTP: outgoing.yahoo.verizon.net

These worked for more than a year on two separate accounts run on two separate Apple computers, until a month ago something just stopped and now we can no longer send a receive mail on these servers through apple mail. We can access the accounts on Yahoo and Verizon online, but not in Mail itself. I get the message "Enter password for Account 'Verizon.' The POP server incoming.yahoo.verizon.net rejected the passowrd for user 'myaddress@verizon.net' Please re-enter your password, or cancel." When the password is entered, the same message pops right back up over and over again, even though the password is right. This is happening with TWO accounts on TWO computers, and absolutely nothing is changed, not even a software update. I've been on the phone with verizon for hours, and they insist this is an Apple problem, since the server works fine off the yahoo website. I've tried deleting the account, setting it up again, using incoming.verizon.net instead of incoming.yahoo.verizon.net . . . Does anyone know what is going on, or has seen this before? It's getting really inconvenient to have these accounts offline when nothing has happened.