BUG: dsync and folder names with "@"

Hello,

dovecot version: 2.3.9.2

When I use dsync: /usr/bin/dsync -v -D -o plugin/quota= -f -u my@email.dom backup maildir:/tmp/mailbackup/Maildir it always stops when it comes to a folder with an "@" in its name. Error Message: Warning: Mailbox changes caused a desync. You may want to run dsync again: Remote lost mailbox GUID (maybe it was just deleted?)

I dont know if it makes a difference, but my dovecot uses mdbox and the backup export is maildir.

Hans