Multiple Munin UNKNOWN messages

[counterpoint]

When a server or communications are down, it causes a cascade of “Munin UNKNOWN” emails. Followed later by a cascade of OK emails. One email for every active plugin. It would be better to get only a single email when a server cannot be contacted. Or when it comes online again.

[BETLOG]

Filtering in munin.conf is a good way to deal with that:
contact.warn.command if [ "${var:worst}" != "OK" && "${var:worst}" != "UNKNOWN" ]; then mail -s .....