Background Job not sending mail to SOST

I have a Custom transaction scheduled to run as background job, This transaction is maintained with Shared Distribution list

System should send the Spool generated by background job to SOST and to the eMail ID maintained in Distribustion list

But this functionality is not working, this is working in unit testing client, but not working in Quality testing client

I checked all SCOT settings, and D/L settings, they are all similar, is there anything i am missing?

Thanks

DD