Today there was an alert from unknown source for the correct reason of Job failure in SQL agent scheduled job.
The heading says
"FW: SQL Server Job System: 'Backup empower' completed on <server name>.". But actually the backup was failed and the regular alert came to DBA team.But this alert went from different email profile.
Check the dbo.sysalerts, there is various information within the table.If you don't know where it came from , you may need to run this on various servers use msdb go select * from dbo.sysalerts