Django-post_office email with custom template

post_office_templated_email.py

def send_email(self,
               template_name,
               context={},
               attachments={},
               base_message_template='post_office/email_base_text.html',
               base_message_template_html='post_office/email_base_html.html'):
    '''
    Try to send email by Django post_office library, with custom HTML template and
    respect of user language.

    Designed to work as method of UserProfile model, which has OneToOne relationship
    with settings.AUTH_USER_MODEL and self.preffered_language attribute.

    '''
    try:
        try:
            tpl = get_email_template(name=template_name, language=self.preffered_language)
        except EmailTemplate.DoesNotExist:
            tpl = get_email_template(name=template_name)
        context['language'] = self.preffered_language
        translation_activate(self.preffered_language)
        base_message = get_template(base_message_template).render(Context(context))
        base_message_html = get_template(base_message_template_html).render(Context(context))

        subject = tpl.subject
        message = base_message.replace("MESSAGE_TEXT", tpl.content)
        message_html = base_message_html.replace("MESSAGE_TEXT", tpl.html_content)

        mail.send(
            [self.user.email],
            settings.DEFAULT_FROM_EMAIL,
            subject=subject,
            message=message,
            html_message=message_html,
            headers={
                'Reply-to': '[email protected]',
                # make sure you have this url - much better for usability and less annoyed
                # users and spam filters
                'List-Unsubscribe': '<https://your-domain.org/some/unsubscribe/url/>',
            },
            context=context,
            attachments=attachments,
        )
        translation_deactivate()
    except Exception as e:
        misc_logger.exception(e)
        return False
    return True

It has ugly replacement of MESSAGE_TEXT and MESSAGE_TEXT, but it's fine in fact and may be easily replaced by adding {% extends ... %} in database-stored template and {% block ... %} usage.

By the way, how would it work if we add {% extends '...' %} now?..