Unattended-upgrades mail only on error or reboot?

I have unattended-upgrades installed on several servers, some version 12, some 14. I would like to enable MailOnlyOnError for them but would still like to receive email notices when an update requires reboot.

Will I still receive "reboot required" notices with MailOnlyOnError enabled?

Thanks!

Here is a solution based on an answer in this discussion. The trick is that the request for a reboot is indicated by the presence of the file /var/run/reboot-required.

Create a file /usr/local/sbin/email_update_required with the content

if [ -f /var/run/reboot-required ]; then
    echo "A reboot is required following updates to server `hostname`" | mail -s "Reboot Required" <mail-address>
fi

Adjust <mail-address> (for example to root or your personal email address). Check the permissions and make the file executable.

Put the following line into your root crontab (sudo crontab -e)

00 08 * * * /usr/local/sbin/email_update_required

(It runs the email_update_required script every day at 8 o’clock, adjust as needed.)

I've applied the above method to a Ubuntu 14.04 server with unattended-upgrades and MailOnlyOnError true", and it works.

Still, it would be nice to have a more "official" Ubuntu or unattended-upgrades way to get those notification mails. A switch similar to MailOnlyOnError would be great.