If you use OQRS, it's highly likely that Japanese, Chinese, Russian or other non-Western characters will appear in the address data for your QSLs.
You must configure PayPal to support this. Marios 5B4WN has prepared this video to explain how:
If you cant find the link, login to paypal and follow this link:
Choose language encoding button from the bottom of the screen
then choose MORE
and change to UTF-8