We export some low value goods to New Zealand and I zero rate the sale as per HMRC. My problem seems to be that I have no real proof of postage to a New Zealand address as we use a franking machine. I have paperwork for the payment through paypal with a New Zealand address but that's it. Should I be sending them through the post office so they can give me a receipt showing that they were sent to New Zealand?
You should read HMRC Notice 703, para 7.5, to confirm that you understand HMRC guidance.
Part of the evidence is the sales order, with delivery address. Also, as you mention, proof of payment with payee's address details. This, together with the postal evidence as per the HMRC Notice, should suffice.
Thanks for the reply. It sort of answers my question that when sending something via royal mail I'm better off not using the franking machine due to lack of evidence.
I have taken franked mail into the post office for a certificate of posting - these days that is a 'till receipt'. Even though I wasn't paying for the postage I didn't have any problem. When the post collected I left a 'certificate' with the parcel and the postman signed it when collecting the parcel.