tl,dr
My failed email status has been the same since I posted #137 in the other thread on March 28th of last year. But tonight I finally got Thunderbird to work.
Background:
My issue had been Thunderbird could receive migrated copper.net mail, but attempts to send from Thunderbird came back "user/password invalid." The identical usernames & passwords worked fine on the 'new' webmail.
I had set up automatic forwarding of both migrated copper.net email accounts to my last working server account at Time-Warner/Spectrum. Administrator Matt hadn't been seen on the Migration Issues thread for 13 days. I completely gave up trying to fix things. Now I figured after a year, I need to either get Thunderbird to work or cancel copper.net.
The renewal bills came in October and I paid them, as I was still getting a few emails forwarded from the two accounts, and I held out hope that once the dust settled, I might be able to fully use Thunderbird again.
My Windows 7 laptop I had been using eventually slowed to the point of being unusable. I got a replacement laptop with Windows 11 in June. Tonight, after finally reading the rest of the migration thread and not finding any reply to my problem, I tried adding my two copper.net accounts to the new Thunderbird 102.8.0. I used Matt's settings from Post #1, AND THIS TIME, IT WORKED! I got downloads of copies of my incoming messages that had been forwarded dating back to February 21 of last year. But sending a reset message to
resynch-me@everyone.net failed: user unknown. At first I thought I was the unknown, later I suspected the resynch mailbox had been disabled.
History:
At home, I have Time-Warner Spectrum over cable. My speeds on a coax line upgraded to 200 Mbps test at 96/12 Mbps, with the choke point likely being my WiFi.
We also bought a fixer-upper future home out in the sticks. When we bought it, the internet choices would be either dial-up or satellite. The previous phone line ran over 37,000 feet of twisted pair copper from the central office, so DSL that far out was not an option. The copper was all buried decades ago by GTE. And there was no 2G/3G cell service.
New phone company owner Frontier ran fiber optic lines overhead on the power poles, where passing logging trucks can and have snapped them. The new phone line I got together with DSL internet ran about 5000 feet overhead to a new DSLAM, and then by the new fiber optic 8 miles back to the central office.
Frontier did not offer email servers, they wrote "Get Yahoo!"
Yahoo! accounts have been hacked so many times that I knew I needed an alternative, and I found copper.net. I got copper.net accounts to supplement the Spectrum server, which will eventually go away.
Frontier finally offered fiber to the premises. (Previously: ME: "I want fiber optic." CALL CENTER: "We don't have fiber optic installed in your town." ME: "It's on a pole ON MY PROPERTY." ) My new fiber optic internet service is throttled at 15/15 Mbps due to central office backhaul bandwidth. That's fast enough for now. And Verizon Wireless 4G VoLTE voice calling now works somewhat OK there, even with no 'bars" of signal strength.