Offhand, I don't think I've ever mailed an International letter or package.
Is return postage something that, normally, my local post office would help me with? E.G. do they have some method of marking or adding post to a package that would be accepted globally (or at least within the destination country)?
"""
United Kingdom
The Royal Mail stopped selling IRCs on 31 December 2011[26] due to a lack of demand. United States
The United States Postal Service stopped selling international reply coupons on 27 January 2013.[27]
"""
https://en.wikipedia.org/wiki/International_reply_coupon#Uni...
That explains why I was confounded in my efforts to search within USPS results.
That's the International Reply Coupon mentioned in the article, but it's not supported by all countries.
I think I've sent far more international letters and parcels than domestic. Christmas cards for elderly relatives in the country I was born in, and postcards when I travelled abroad.
Some obscure things I sold on eBay were mostly sent abroad.