Comment 12 for bug 1641671

Am also experiencing this from about 30 Ubuntu 16.04 machines in our office. We get very regular e-mails that the flash plugin was updated, and there's no "normal" way to silence them. As a workaround, we change /etc/cron.daily/update-notifier-common to send its output to `/dev/null`, but this will be rolled back with an change of update-notifier.

I think that the last patch, posted by Roman Odaisky, will fix part of the issue. However, for the Flash player, at some point, `apt` is called which also produces output that is e-mailed in cron. It might be best to just change the cronjob to redirect its output (perhaps also stderr) to some log file.