When I try to move a mail to mailbox named Test, an exception is thrown:
Cannot copy mail to mailbox 'Test': [TRYCREATE] UID COPY Invalid mailbox name
My mailbox is hosted on wedos.cz. I was further investigating why is this happening and I figured out that if the mailbox name is not prefixed with a server name (e.g. {foo.bar.net:993/imap/ssl}), it works.
The problematic line of code is here https://github.com/greeny/MailLibrary/blob/master/MailLibrary/Drivers/ImapDriver.php#L396
I do not know if the server name is required or if it could be omitted. Maybe some configuration option/switch removing the server name should be added.