Attach mail sent through CL_BCS to Sales Order using GOS

Hi

we are sending an email to customer using our custom program . This email, should be seen as part of the attachments when anyone opens the sales order. I know that GOS can be used to create attachments in Sales Order. But can we attach an email that is sent from SAP to the attachments list?

Please let me know if this is possible.

Thanks,

Vishwa.