I've worked with Don Farber on this back in 2009. Here was his response back then:
""Regarding the tracking of deleted records, the answer again ""yes -- KnowledgeSync does support this"" but the solution is not quite as easy as in monitoring for changed records.
To identify deleted records, the suggested approach is to use database triggers, as triggers can be kicked-off when a record is deleted from the database. In SQL, the trigger writes out audit details of the record a nanosecond before the record is physically removed from the database, so KnowledgeSync has access to the deleted record's details.
In KnowledgeSync, the trigger then kicks off a corresponding KnowledgeSync event which sends alerts, executes actions, et cetera.
I have one of our technicians looking into the options for tracking deleted records in a non-SQL database, and I'll get back to you with details on that as soon as I know them.""
Here's a thought (assuming 4.4 or above): keep a mirror table to the item table, but do not add the usual script logic to delete records from the mirror. The mirror should contain fields that you would want to see in the alert. The query would have to be set up to only show records that exist in the mirror table, but do not exist in the CI_Item table. The event would only send emails for new records.