I had the same issue with my verizon with yahoo account link. Verizon says they will allow you to read your emails up till April 30th and all emails are being forwarded to fairpoint.
This is what the page said when you logged into Verizon.net:
You have been identified as a FairPoint Communications Internet subscriber. Please visit www.myfairpoint.net to learn more about FairPoint's Internet products and services.
IMPORTANT: All messages sent to your verizon.net email address are being automatically forwarded to your new myfairpoint.net address. This forwarding will continue until April 30th. You can continue to access your Verizon Webmail account to view stored messages until March 1st. To do so, please visit »webmail.verizon.net
However, when you log into webmail.verizon.net you are directed to a yahoo logon page if you are using verizon/yahoo email, when you sign in there you get a dead end page stating, verizon pulled the plug on your yahoo account so you are SOL ( I thought). On the page that yahoo puts up, it gives you a number for the Verizon member support line. I don't remember the 800 number, but it is there. I called them up and answered 'I don't know' on all the questions the computer asked about your account(important), until I got to a live person.
Once I got to a live tech person I explained I was with fairpoint and that their site said I would have access to my emails until April 30th, but my verizon/yahoo account has been disabled prematurely. She said it was not a big problem and re-activated my account and sub account right there, so I can access my old email. From phone call to results took about 5 minutes... (wow)
Once I got access back, I moved over all the emails they failed to move over to my fairpoint inbox. pretty much all of January was not moved. All email after Feb 1 is already being delivered to the new account and not going to verizon account.
So once you get the email back on, forward all of your important stuff to either fairpoint or another email account, because you don't know when yahoo may shut it back down and delete it. Also copy anything over they did not do.
Hope this helps a few people who are frustrated as I am.