As a Ist time Seller.

[truckpump]

How can I check that the buyer has received the Shipping/Tracking # set up at the post office?

[DPCreations]

The buyer doesn't need the tracking number; PayPal does.  But, you can email the buyer the tracking number so the buyer can track progress.

[truckpump]

Thanks Kudos, Have sent the Buyer the tracking #.Truckpump.

[Whac-A-Mole]

Go to USPS website and enter your tracking number and ask USPS to send you email notifcation of progresss to you and to your buyer email address.