def is_managed_key(key):
	"""
	Return True for configuration keys which should be managed by this
	plugin. This is to let keys for other configuration settings remain the
	same.

	:param str key: The name of the configuration key.
	:return: Whether or not the key should be managed by this plugin.
	:rtype: bool
	"""
	if key == 'mailer.company_name':
		return False
	if key.startswith('mailer.'):
		return True
	if key in ('remove_attachment_metadata', 'spf_check_level'):
		return True
	return False