Sends an email to staff in listed in the setting
    ``ACCOUNTS_APPROVAL_EMAILS``, when a new user signs up and the
    ``ACCOUNTS_APPROVAL_REQUIRED`` setting is ``True``.

def send_approve_mail(request, user):
    """
    Sends an email to staff in listed in the setting
    ``ACCOUNTS_APPROVAL_EMAILS``, when a new user signs up and the
    ``ACCOUNTS_APPROVAL_REQUIRED`` setting is ``True``.
    """
    approval_emails = split_addresses(settings.ACCOUNTS_APPROVAL_EMAILS)
    if not approval_emails:
        return
    context = {
        "request": request,
        "user": user,
        "change_url": admin_url(user.__class__, "change", user.id),
    }
    subject = subject_template("email/account_approve_subject.txt", context)
    send_mail_template(subject, "email/account_approve",
                       settings.DEFAULT_FROM_EMAIL, approval_emails,
                       context=context)