Alert Triggers say when an Alert should be sent. Alerts can be triggered by five different system level events in Business Central.

InsertionWhen a record is created
ModificationWhen a record is changed in any way
DeletionWhen a record is deleted
Field ChangeWhen the specified fields in a record is changed
EventPredefined important events in Business Central, e.g. any posting action for an Item

You may need to change which method your trigger uses if you receive too many alerts, or alerts at the wrong time.

The trigger can be set during the Creating a new Alert process, or can be adjusted on the Alert Entries page.