This is done by saving the notices in the message_queue table with
type 'print'. The notices are generated from a notice named
HOLD_PRINT. At the end of the day, they are dumped to an HTML file and
marked as sent by a new cronjob.

This setup is intended to be temporary; modules/batch/ shouldn't be around
forever.

Mandatory SQL:
INSERT INTO message_transport_types (message_transport_type) values ('print');