I'd agree with Steve, a courier service offers the safest route.

To answer your specific question though, I stand to be corrected in that quite a few of the Central Post Offices in Metro Manila (and other places too) have counters for Post Restante mail.

The items addressed to Post Restante are retained for one month.

The Central Post Office in Marikina has one for sure.

Search google for the address of the nearest convenient Central Post office to confirm they have a counter.

Personally, I wouldn't use that service for anything other than postcards or short non-urgent messages etc.

Certainly not for important papers, gift parcels etc