I have used thunderbird for years.
Using the recommmended settings, it does not login.
I went to keychain and deleted all verizon internet passords entries in login.
I have tried both SSL and no SSL in incoming security and neither works. I have tried putting incoming and outgoing in settings and that does not change anything either.
I tried different ports with no changes.
I have reinstall it 2 x after deleting whole app on iMac OSx latest version.
Some people have been having trouble because of recent changes SOMETIMES giving servers that have a different name from the value in the Encryption Certificate. I don't know if their is anything you can set in Thunderbird to get around this. Some have used various other names that Verizon has used overtime or the AOL name to get different servers. Note that is not a recommended solution but might work for awhile until Verizon/AOL/Yahoo gets this straightened out.
Note: I included yahoo in this list as, for me, I recently started seeing the server getting resolved to a Yahoo Named server.