Duplicate folders "Junk E-Mail" were detected in the mailbox. Therefore the user's connection was disconnected
https://kis.kellogg.northwestern.edu/Pages/ExchangeLinux.aspx
NOTE: Connecting to Exchange using IMAP can produce the following error message in Thunderbird: "Duplicate folders "Junk E-mail" were detected in the mailbox. Therefore the user's connection was disconnected."
To resolve this problem, connect to your Exchange account via Outlook Web Access, and delete one copy of the duplicated folder.