I've been using Thunderbird for many years and recently had a crash that I hadn't noticed. Thunderbird repaired itself automatically but the absolute basic function is defective and I have tried everything, really everything, that is possible. I have checked the settings several times. Thunderbird has checked and confirmed the data on the Telekom server. When I click on 'ready' I get the message that the registration on the telecom server failed. I have screenshots of the entries. I just don't want to publish them here because the background of this blog is not secure enough for me. If there is someone who can advise me personally, I am happy to transfer the shots.