Another football in the Verizon Yahoo/Shuffle are those Verizon customers who were sold to Frontier but had verizon.net email addresses.

Verizon kept control of those lightly-maintained email accounts and pushed them into the Yahoo/AOL infrastructure. Users with a verizon.net email address had webmail access at mail.aol.com.

Verizon didn't make life easy. They changed POP/IMAP/SMTP servers every year or so. Just this May they changed again, from smtp.mail.yahoo.com to smtp.verizon.net - but the old servers still worked until the AOL outage 2 days ago.

During the years in between, customers got caught between AOL's mandate to use OAuth and Microsoft's refusal to support it in Outlook.

FF to now-ish and Verizon is purchasing those same FiOS customers back again. One more smack with the Verizon ping-ping paddle.