Deleting folders in your own mailbox
There can be errors in various email programs when deleting entire folders, these may remain unchanged on the server after an error message.
In Thunderbird/Icedove this can be changed if the option "When deleting a message" is changed to "Remove immediately". The option is located under Tools -> Accounts -> Server Settings.
If this problem still occurs in other programs, please contact the support of the computer operation.