every time an user try to access the junk folder in webmail an error message is displayed and in the logs I see:

May 25 16:18:41 sogod [16279]: [ERROR] <0x0x7f2b860f2c58[NGImap4Connection]> could not select URL: imap://admin@localhost/Junk/: {RawResponse = "{ResponseResult = {description = \"Mailbox doesn't exist: Junk\"; result = no; tagId = 6; }; }"; reason = "Mailbox doesn't exist: Junk"; result = 0; }