After I upgraded to mongerey this error occurs in my email all the time, my previous was mojave.
I did everything like deleting mails from the libraries, reload etc.
MacBook Air 13″, macOS 12.0
Something must have gotten corrupted during the upgrade's download. It sounds like you may have to go into your email app and (1) cancel the account, and (2) set up a new account which can then access the email provider's server.
Something must have gotten corrupted during the upgrade's download. It sounds like you may have to go into your email app and (1) cancel the account, and (2) set up a new account which can then access the email provider's server.
Mail was unable to open this mailbox on the server “”. The server returned the error: Mailbox does not exist, or must be subscribed to
