Error Severity 16 Alert being raised for events where is_event_logged = 0

I have an error level 16 alert set up as follows: USE [msdb] GO EXEC msdb.dbo.sp_add_alert @name=N'Error - Severity 16', @message_id=0, @severity=16, @enabled=1, @delay_between_responses=0, @include_event_description_in=1, @category_name=N'[Uncategorized]', @job_id=N'00000000-0000-0000-0000-000000000000' I was curious why SELECT 1/0; >Msg 8134, Level 16, State 1, Line 17 Divide by zero error encountered. was not raising an error but BACKUP DATABASE MyDatabase TO DISK = 'C:\FolderThatDoesntexist' >Msg 3201, Level 16, State 1, Line 8 Cannot open backup device 'C:\FolderThatDoesntexist'. Operating system error 5(Access is denied.). >Msg 3013, Level 16, State 1, Line 8 BACKUP DATABASE is terminating abnormally. was This post and The blog post it references suggest that SQL Server will only raise events for errors that are logged and this can be found in sys.messages So I queried sys.messages for these error codes: SELECT severity, message_id, is_event_logged FROM sys.messages WHERE language_id = 1033 AND message_id IN (8134,3201,3013) but found that all three are set to 0: Why therefore do 3201 and 3013 trigger my alert but 8134 does not?