python xlsx email attachment (with luigi helpers)

luigi_email_attachment.py

from luigi import notifications, configuration
import smtplib
import email
import datetime

def send_email(subject, message, xlsx_fn, sender, recipients):
    if not isinstance(recipients, (list, tuple, set)):
        recipients = [ recipients ]
        
    config = configuration.get_config()
    
    smtp_ssl = config.getboolean('core', 'smtp_ssl', False)
    smtp_host = config.get('core', 'smtp_host', 'localhost')
    smtp_port = config.getint('core', 'smtp_port', 0)
    smtp_local_hostname = config.get('core', 'smtp_local_hostname', None)
    smtp_timeout = config.getfloat('core', 'smtp_timeout', None)
    kwargs = dict(host=smtp_host, port=smtp_port, local_hostname=smtp_local_hostname)
    if smtp_timeout:
        kwargs['timeout'] = smtp_timeout

    smtp_login = config.get('core', 'smtp_login', None)
    smtp_password = config.get('core', 'smtp_password', None)
    smtp = smtplib.SMTP(**kwargs) if not smtp_ssl else smtplib.SMTP_SSL(**kwargs)
    if smtp_login and smtp_password:
        smtp.login(smtp_login, smtp_password)

    msg_root = notifications.generate_email(sender, subject, message, recipients, image_png=None)
    
    msg_attach = email.mime.base.MIMEBase('application', 'vnd.ms-excel')
    with open(xlsx_fn, 'rb') as f:
        msg_attach.set_payload(f.read())
    email.encoders.encode_base64(msg_attach)
    msg_attach.add_header('Content-Disposition','attachment;filename=%s_%s'
                          % (datetime.datetime.now().strftime("%Y%m%dT%H%M%S"),
                             xlsx_fn))
    
    msg_root.attach(msg_attach)

    smtp.sendmail(sender, recipients, msg_root.as_string())