Comment 2 for bug 260443

The configuration file handling in here needs to be fixed. At the moment, the init script does

  sed "s/FREQ_IN_MIN/$FREQ_IN_MIN/" "/usr/share/update-motd/update-motd.cron" > /etc/cron.d/update-motd

unconditionally. This overwrites the admin's changes without checking or confirmation.

If you ask me, I would ship /etc/cron.d/update-motd as a conffile, so that the admin can change it directly, without any dynamic magic. If you don't want to do that for some reason, you should do an ucf-like approach, create the config file in the postinst if it doesn't exist yet, or use ucf to manage it on package install/upgrades if it exists and was modified. I don't really see the need to do it in the init script. No other package does it that way, and it is higly unusal and also pretty brittle.