JTAlert will only consider deleted entries from your Log during the Rebuild process if the "Crystal Ball" plugin is installed and enabled ;)

Seriously, the "Rebuild Alert Database" is just that a "Rebuild" not an update. The existing database is cleared, all entries removed, and rebuilt from scratch using the result from your physical Log (which now doesn't contain those deleted entries).

The Alert Database is independent of your B4 checks, it is only used to determine if a decoded Callsign will generate one or more Alerts based on your needs. All B4 checks are done against your Log so any deleted Log entries will not generate B4's. Except if you delete the Log entries while JTAlert is running than there is a chance that JTAlert may be using a cached B4 check result rather than an explicit Log B4 lookup result. JTAlert caches B4 checks for performance reasons. A cache (memory) lookup is orders of magnitude faster than a slow disk-based Log lookup.

de Laurie VK3AMA