I'd suggest i-courier mo sa CEM direct, make sure yung address or department ng CEM is correct. You get tracking and a receipt of delivery sa docs mo. Then as soon as naipadala mo, email CEM with as a response to their letter of instructions stating you have sent your response via courier including the documents requested. So comply ka sa instructions nila. Kapag nakuha mo naman ang tracking receipt and signature ng receiver, email CEM again, this time as a notification, na na-receive na ang additional docs mo, and include a copy of the tracking receipt. Di naman bawal mag-notify sa CEM ng important details about your application (i.e. submission of requested docs)...
Even if sa Makati ka malapit, even kung buhay pa ang maildrop sa basement ng RCBC for submission of docs - my view is you don't get that feeling of security of your docs submission kung walang signature ng tumanggap.
.../atb