I have posted this solution previously, so forgive me for repeating it if you've all seen it before.

Totally agree i-love-my-sheep that get them to stamp them, then move aside while you photograph them, allowing the next person to be served is a good idea.

I was having major dramas with large letters going missing some time back & so reported it to Aust. Post and spoke to PayPal, also determined, they were going missing from the red street box !

While PayPal have told me this way of covering yourself as a Seller is totally acceptable, on ocassions when I have posted on the boards, others say it is not acceptable as it does not prove Buyer received the item, so you can all be the judges.

Here's what I do  :-

When I type & print my address labels, I print two copies.  One I use as labels and the second I take with me to the PO.  The staff check my mail against the list and then stamp the list for me as proof of postage.  No need to take photos 🙂

Since keeping records this way, I have still had several scammers Buyers message to say their items have not arrived, so I very politely message back and explain :-

• Just for their peace of mind that the item was actually posted I am including a copy of the PO stamped document/receipt (which I take a photo of and blank out other Buyers names and address's - I just leave their suburb & Postcode showing)). 

• I also ask them to check with their local PO to ensure it's not being held as it is a padded envelope.

• I also tell them I am happy to send a replacement if it is not at the PO (This of course gives them an out) 

Miraculously, the item usually turns up the next day. 

Since using this method I think I have only had to replace 2 items out of 100's sent.  Previously I was replacing anything up to 2 or 3 for every 20 sent.  I have also found asking the staff to attach a label as opposed to normal postage stamps seems to help (looks more official) Oh, and, I only ever lodge over the counter - I never use the red box anymore !

So, it could be a mixture of solutions . . . . . . .