IMAP4 client class over SSL connection
Instantiate with: IMAP4_SSL([host[, port[, ssl_context[, timeout=None]]]])
host - host's name (default: localhost);
port - port number (default: standard IMAP4 SSL port);
ssl_context - a SSLContext object that contains your certificate chain
and private key (default: None)
timeout - socket timeout (default: None) If timeout is not given or is None,
the global default socket timeout is used
for more documentation see the docstring of the parent class IMAP4.