Use a tPostJob component and add the logic to trigger the email to that component. The tPostJob will always run. During your job you will need to find a way of identifying whether the job has failed. An easy way is to set up a globalMap variable that holds a key of "Failure" and a value of true. If the job proceeds to the very end without error, after that, set the "Failure" value to false. Then the tPostJob will fire. Trigger the email logic based on the value of "Failure" being true. If the job is successful, that variable will have changed it value to false, therefore the email will not send
