Extend configure_host to accommodate CA certificate authentication

[keberlin]

Would it be possible to extend the existing Connection::configure_host to allow a CA certificate file to be specified?

The extra code looks like this:

    if self.mail.use_tls:
        **# Change to support CA certificate authentication
        cafile = current_app.config.get("MAIL_CAFILE")
        context = ssl.create_default_context(cafile=cafile)**
        host.starttls(**context=context**)