If a batch job is sending an email regarding a leaver, this signifies that the data source is not set up to filter out leavers.
To resolve this issue, the data source of the batch job will need to be altered.
To limit the notifications to just send for current employees, you will need to tick Effective Status in the data source of the relevant batch job, then type current in the criteria.
This will then limit the employees being brought back into the data source.
If you require assistance changing the data source of a batch job, please contact your account manager to discuss your consultancy options.