40+ Certificate Chain Error PNG

40+ Certificate Chain Error PNG. Message=a connection was successfully established with the server, but then an error occurred during the login process. Self signed certificate in certificate chain.

Error Unable To Establish Certificate Chain While Installing New Certificate
Error Unable To Establish Certificate Chain While Installing New Certificate from support.citrix.com
Unable to validate certificate chain: Tls handshake failed nov 23 10:59:29: C = us, o = let's encrypt, cn = let's encrypt authority x3 error 2 at 1 depth lookup:

These apparently do not use windows trust certificates when building the certificate chain.

When starting mailbox, you see the following: * the host certificate chain is not complete. A 'certificate chaining error' occurs when the provided chain of certificates cannot be validated. When starting mailbox, you see the following: