Bug report

imaplib does not quote command arguments, which leads to problems e.g. if a user specifies a mailbox with a name that contains a space.

>>> imap = imaplib.IMAP4_SSL('server', 993)
>>> imap.login('user', 'password')
>>> # Note: mailbox named "TPS Reports 2009-2010" does exist on server
>>> imap.append(b'TPS Reports 2009-2010', None, None, b'From: nobody\r\nTo: nobody\r\nSubject: nothing\r\n\r\n')
('NO', [b"[TRYCREATE] Mailbox doesn't exist: TPS (0.001 + 0.000 secs)."])

It appears that this functionality was removed by accident. A call in _command to a function _checkquote was commented out in fb5faf0 and then the function and everything connected to it was removed in f241afa.

Your environment

• CPython versions tested on: 3.10.4 (has issue), 2.7.18.4 (does not have issue)
• Operating system and architecture: Void Linux, ppc64el
• IMAP server tested with: dovecot 2.3.18