Do you think I should be more careful will the photos I post on this forum, more selective?
That is your decision. People enjoy seeing photos, but I do not advocate violating intellectual property laws. I have many, many photos (and even more postcards) in my personal collection. But if the item is under 75 years old, I would have to get permission from the copyright holder. Images older than 75 years are also subject to intellectual property laws - not the original print but prints from the original. If you order a photo from the Royal Archives, the print you receive will be copyrighted, even if the image is older than 75 years.
This doesn't stop people from doing it. I don't want to get into an argument about it ... It's not up to me to stop anyone = but I won't do it. In the early 1990s, I took action regarding intellectual property, but it was to me personally ... as I said it is your choice.