I have a couple of old letters from a Michal Dubiel, addressed to my grandmother as "Kochana Stryjenka" so he was my mother's cousin. The return address is:
Suchowola pecs Osiek pow Staszow
The letters are undated and there is no postmark on either, as the stamps were removed, so I'd place them in the early 60's (when my brother and I collected stamps) but after 1963, otherwise they'd be addressed to my grandfather. I also have an Easter postcard addressed to her, signed with other names, but no family name, so don't know if they're relatives or friends. It was sent in an envelope (missing) so there's no return address.