How do you configure a SQL Server Agent job to send an email alert if it fails?

You configure Database Mail with a valid mail profile, create an operator representing the person or team who should be notified, and then set up a notification on the job itself specifying that an email should be sent to that operator whenever the job fails, giving your team immediate visibility into problems without needing to manually check job history.

EXEC msdb.dbo.sp_add_operator @name = 'DBA Team', @email_address = 'dba@example.com';
EXEC msdb.dbo.sp_update_job @job_name = 'NightlyBackup', @notify_level_email = 2, @notify_email_operator_name = 'DBA Team';