Sends an email with defined parameters from the .ini files.

    :param recipients: list of recipients, it this is empty the defined email

        address from field 'email_to' is used instead

    :param subject: subject of the mail

    :param body: body of the mail

    :param html_body: html version of body

    """

    log = get_logger(send_email)

    DBS = get_session()

    email_config = config

    if not recipients:

        # if recipients are not defined we send to email_config + all admins

        admins = [u.email for u in User.query()

                  .filter(User.admin == True).all()]

        recipients = [email_config.get('email_to')] + admins

    mail_from = email_config.get('app_email_from', 'RhodeCode')

    user = email_config.get('smtp_username')

    passwd = email_config.get('smtp_password')

    mail_server = email_config.get('smtp_server')

    mail_port = email_config.get('smtp_port')

    tls = str2bool(email_config.get('smtp_use_tls'))