smtp_url can be None, so do not treat it as string, allow to take different
actions (like doing nothing).

getMessageList shall not be available on normal mail host. It will be available
on one coming from live tests, so in such case die immediately.

It will be used to represent various Computer models.

It will be used to create group of Computer.

Access Token behaviour is configured on the portal type level.
The token ID is used to directly fetch it without using the catalog (faster
access).

This is known to slow down setResource a bit