I know this is an old thread, but since its been revived I am going to add in my two cents and something I have recently learned.
I got this straight from Paypal customer service - I lost over an hour of my life on the phone with them to clarify this. You can pay $1.30 extra at the PO for something called "Certificate of Mailing". It's just a little form they stamp and proves you mailed a package to whatever address on whatever date. According to the guy I spoke with, this will protect a US seller in the instance of a "item not received" claim from an International buy on First Class International mail.
I do ship to Canada, but I admit I am a bit leery of it, even after all these years. I put in my listings that I must "know" you. So, I'm not selling to Canadians that aren't active on non-FSOT forums here. I want them to be invested in the forums and familiar to me, otherwise I'm not taking the risk of a bogus Paypal claim.
If I am selling something for $10ppd, I know it will cost me $2.50 (round number example) to ship to the US first class. So if someone Canadian wants to buy, I subtract $2.50, add exact postage and add $1.30 for certificate of mailing. I do take a picture at the PO counter to message to the buyer.
Selling to Canada is a lot more work that to the States. I love my Canadian mama friends and I am happy to make a special trip across town to the PO, but honestly, it is a lot more involved. Maybe the PO isn't such a hassle in Canada?
Can y'all track packages within Canada like we can within the States?
Mama to Henry (01.07), Catherine (09.11), Audrey (04.14), Clare (09.15) and our newest addition, coming July 2017!