Certificate Error

I have reset my computer, copied back the ~/Library/ApplicationSupport/Mailspring folders to my fresh installation. I get an error on some mailboxes, saying “Certificate Error” when i try to login.
I can login with “use insecure login”. The certs on my linux mail server are all up to date. not due to renewal. A ssl checker tells me, all certs are valid.

So how can i fix this issue?