Create an external url_for by using a custom base_url different from the domain we
    are on
    :param endpoint:
    :param base_url:
    :param kw:
    :return:

def _url_for_email(endpoint, base_url=None, **kw):
    """
    Create an external url_for by using a custom base_url different from the domain we
    are on
    :param endpoint:
    :param base_url:
    :param kw:
    :return:
    """
    base_url = base_url or config("MAIL_EXTERNAL_BASE_URL")
    _external = True if not base_url else False
    url = url_for(endpoint, _external=_external, **kw)
    if base_url and not _external:
        url = "%s/%s" % (base_url.strip("/"), url.lstrip("/"))
    return url