Every 2 years, when a new Ubuntu LTS version comes out, I need to migrate my cloud based mail server. After I have transferred the domains and set DNS to the new server IP, I always have the problem, that my existing thunderbird imap mail accounts don't work properly anymore. K9 mail on my android devices doesn't have this problem. Sending mails does work, but the imap connection to my mail accounts is broken. I tried using the IP of the new server instead of its DNS name, but this didn't help either. The only way that works, is to add a new account. This is very nagging as I then need to manually edit all my adapted settings and my various mail identities. Is it a generic problem with TB, possibly with the server certificates? Or is there another way to change the imap server of an existing account?