Una all we can do is to share our opinions.

I lived and worked in exact same position in both Europe (country in Europe close geographically and culturally to Sweden-so I am aware) and US. On both continent it’s very cool to keep in touch with teachers. There is very little to no differences.

I personally am very close to a lot of students and due to nature of my specific position and my personality am very involved with kids and their families and am often contacted years after. It’s all good and dandy.

What Sara described is a different situation imho. She is more than welcome to look up addresses and send cards. I personally would be uncomfortable. If the person never ever spoke to me for 20 years and didn’t acknowledge me running into me but then was looking up where I live, I’d be uncomfortable. But we are all different people. This teacher might be perfectly fine and even happy to get a card. I am not an authority on anything. Just sharing my opinion

Of course it’s fine to send a card