Most internet search hits are still showing up with the Mandaluyong Post Office number which is +63 2 719 0716. This number is no longer operational. If you need to call them to validate postal notifications then the following number was provided by the PhilPost customer care: +63 2 535 2131.

NOTE: The number is ringing and no longer responsive. The PhilPost site also removed the numbers in their web page. This is a disappointing turn of events. 🙁

[CAVEAT] I am not affiliated with the Philippines Postal Service. I am an ordinary private Filipino citizen who uses their service and publishes this blog entry as a public service.
(Paunawa: Wala akong kinalaman o koneksyon sa Postal Service ng Pilipinas. Ako ay isang ordinaryo at pribadong mamamayan ng Pilipinas na gumagamit lang din ng serbisyo ng Post Office. Itong post na ito ay isang kawanggawa lamang sa akin blog.)

[UPDATE 2016/09/19] Visitor Monica said the 535-2131 number is not working last July. I called the Mandaluyong Public Information Office and they confirmed that the post office still has that number. The number is ringing when I tried it but I didnt have the time to wait for somebody to pick it up. If the number remains non-functional then please try calling the main office using the numbers posted at https://www.phlpost.gov.ph/