The post office has no idea what eBay does. All I know is this, you cannot purchase tracking for GPM from the PO. Since eBay began international shipping, I'm able to see when an item arrives. I'm guessing it's from the customs number created. I have no idea how they're doing it. I only know I can see when packages are delivered. Like I said, a watched a package go to Spain in 3 days and when it arrived, I saw it say, delivered.
Yes, I ship through the 'My eBay' page. The integrated shipping they offer. I love it. I've had very few issues with it. I know a lot of sellers hate eBay. Hate eBay's tools and all that. I dunno, I use a lot of eBay tools and I love all of them.
Try the regular integrated shipping through your 'My eBay' page. Make sure you get a telephone number for all of your international buyers. Otherwise, you cannot print out a shipping label. If you ever can't get one, use your own if you have to.
Try it and let me know how it goes.