Emails about job status are being sent to people that were on the job at one time, but have since been removed. Looking at the job itself the email addresses are not in the job or in tools-> option-> email configuration.
The backup task was originally setup in 2010 on version vRanger 4.x and has had upgrades done over the last couple of years all the way up to version 5.3.1.
Removing the old backup task and Recreate a new backup task will solve this issue.