If using an IMAP account results in an error such as "Too many connections" when retrieving or moving emails, you can reduce the maximum number of maintained server connections and disable the IDLE command in the settings of Mozilla Thunderbird, Outlook, and similar email clients.
For example, in Thunderbird: Settings -> Server Settings -> Advanced. However, this does not help if the IMAP account is used by multiple clients, as the method described above only addresses the symptoms, not the underlying problem. In this case, you can increase the number of allowed connections in the server settings.
