# Establish a secure connection to a server that does not have a certificate
# signed by a trusted certificate authority (CA).

import ssl

from imapclient import IMAPClient

HOST = "imap.host.com"
USERNAME = "someuser"
PASSWORD = "secret"

ssl_context = ssl.create_default_context(cafile="/path/to/cacert.pem")

with IMAPClient(HOST, ssl_context=ssl_context) as server:
    server.login(USERNAME, PASSWORD)
    # ...do something...