Repeating IMAP error

I’m getting the following error logged every 20 minutes:

16:25:57 MYNAME@MYISP.co.uk [IMAP]  MailClient.Protocols.Imap.FolderOpenException: Cannot open folder “MYNAME@MYISP.co.uk/qmail.”. ([SERVERBUG] Internal error occurred. Refer to server log for more information. [2017-05-30 16:27:28])

There is no folder called ‘qmail’ but there is a file called ‘qmail’ in every folder on the email server. eM Client seems to want to treat the one in the root folder as a folder.

Any comment at all?

I’d like to be able to fix this but, if I can’t, I might as well look for an alternative email client.