Misc Django Utils. Including mail a Django Group

misc.py

from django.conf import settings
from django.contrib.auth.models import User, Permission
from django.core.mail import EmailMessage, mail_admins, send_mail, EmailMultiAlternatives
from django.db.models import Q
from django.utils.html import strip_tags


def mail_group(codename, subject, message=None, debug=False, html_message=None):
    perm = Permission.objects.get(codename=codename)  # 'get_billing_emails'
    users = User.objects.filter(Q(groups__permissions=perm) | Q(user_permissions=perm)).distinct()

    # default html_message to message if missing
    if not html_message:
        html_message = message

    # Default message to html_message if it's missing.
    if not message:
        message = html_message
    message = strip_tags(message)

    # Useful info so you know where the email came from
    html_message += "\n\nMessage sent because you're a member of the group %s." % codename
    message += "\n\nMessage sent because you're a member of the group %s." % codename

    # html_message should use <br> instead
    html_message = html_message.replace('\n', '<br/>')

    if not debug:
        emails = [u.email for u in users]
    else:
        emails = [e[1] for e in settings.ADMINS]
        message += "\ndebug is True"

    #send_mail(
    #    subject, message, settings.DEFAULT_FROM_EMAIL, emails,
    #    fail_silently=False,
    #)
    msg = EmailMultiAlternatives(subject, message, settings.DEFAULT_FROM_EMAIL, emails)
    msg.attach_alternative(html_message, "text/html")
    msg.send()