In Exchange 2016 (and 2013) you can check the health of your server. If you run the following command:

• Get-Serverhealth -Identity <ServerName>

You will get a long list of information. To narrow this down to UnHealthy Alerts, you can run the following command:

• Get-ServerHealth -Identity <ServerName> | Where {$_.AlertValue -eq “Unhealthy”} | ft -Autosize

This will return the following information:

As you can see above, we have an unhealthy alert called SmtpProxy. You can run the invoke command which will give you the following:

You get a warning “Could not find assembly or object type associated with monitor identity….”

If you head over to this Technet article you will notice that the probe name is set to none, which is why you getting this warning.

You will need to do some deeper digging in the event logs etc. to find out why this item keeps going offline.

Hope it helps.