You have followed the instructions in KB - https://helpdesk.kaseya.com/hc/en-gb/articles/229034308-Agent-Offline-and-other-alerts-are-not-generated
The process fails with the error:
[Microsoft][ODBC SQL Server Driver][SQL Server]The datediff function resulted in an overflow. The number of dateparts seperating two date/time instances is too large. Try to use datediff with a less precise datepart.
/inc/suspendUpdate.inc, line 46
The issue happens when an agent installed on Mac OSX has suspended alarms and the date time of the Mac endpoint reverted to a 1904 date, which can happen during some failure events.
Resolve the date issue on the Mac endpoint and remove the alarm suspension from the agent. The, re-run the emailNotify.asp page and make sure you get a blank page and the error is gone. You can then re-apply the alarm suspension.