I am not sure if you are running latest BO server or running older version of BOXI service. BCC option is available in later version of Business Objects.
Refer SAP Note: 1369269 - Unable to Schedule reports through BCC
Symptom − 'BCC" option not available while scheduling reports to email.
Reproducing the Issue − Schedule a report with destination as email.
Environment − Business Objects Enterprise XI 3.1
Resolution − The ‘BCC’ option is currently not supported by the product.
As per SAP Note: 1626654 - How do you specify a BCC entry when scheduling documents to email?
The ability to specify the BCC field has been implemented with SAP BusinessObjects BI Platform 4.0 Feature Pack 3 (FP3).