IMAP Account Suddenly Stopped Working (Says "Mailbox doesn't exist:)

My IMAP email account just stopped working. I continually get the message that the mailbox doesn’t exist. I haven’t changed any settings, and I am still receiving mail on my other email clients. Everything was working fine but stopped working on January 6th. My Gmail email account works properly, but my IMAP account does not.

Does it help if you remove the current IMAP e-mail account and add it again?

Please make a backup of the data directory of eM Client first, before removing/adding the e-mail account!!!

You can find the used data directory under Tools --> Settings --> General --> Storage:

Hi, go To tools - accounts - your account and tell me if you have IMAP tab visible. If not then remove and add account again , do not forget to export your data first (if they have not been synchronized to the server)