Background Job to autodelete emails in waiting status in SOST

Hello,

I would like to have a weekly background job that deletes all emails in waiting status in SOST. Is there already a SAP standard job for this or do I need to consult ABAPers to create a program to do this? Actuall the emails that I want to delete are those which came from Workflow (although I'm fine to delete all emails in the queue). I hope you could help me in this. Thanks!