I'm wondering if there is a ddns service that can email me if a device fails to check in. This is what's done with Panamax Bluebolt and Wattbox OVRC.
It seems this would be a great asset to sell a client on and get some recurring revenue.

Why not just sell a Wattbox or BB so that you can take a shot at fixing the problem remotely to justify the RR?

Ihiji

or we also set up email notifications in a Mikrotik to alert us when troublesome equipment stops responding to pings

You can use a service like monitor.us or another of the many ping-based services. You need an external IP for it to work, though.

Some devices will generate their own messages when they fail.

You may also check if the device does SNMP. There are services that will alert if SNMP fails to check in.

Also, some routers do not actually check in with DDNS on a regular basis - only when something changes (ie. a connection goes down).

This was a problem with Dyn's original free service (when they had it) and some routers (I owned one), because they'd deactivate an account if you hadn't updated it for 30 days... and in order to prevent unneeded load on those free servers, routers stopped updating unchanged information at all. Then they changed to manual verification every 30 days, so it became a moot point... and then no free accounts, so it didn't really matter.

Also, even if you did find a service that would notify you - what kind of reporting period would you actually be getting? Once a week? Even once a day? Doesn't seem like a reasonable notification time.

As suggested, you need a proper monitoring service. There are many out there to choose from.

"As suggested, you need a proper monitoring service. There are many out there to choose from."

I am familiar with ihiji and blue bolt, but they are centric to our industry. Are there more IT focused monitoring services that would we should be looking at?