What inspires people who have just made friends with you via email, to immediately place you on their, "send to everyone" list?

Two people I met this week via my WWII research, have decided to now send me jokes, political commentary and whatever else, ad nauseum. All I ask is that everyone stop and think before they do things like this. Not everyone in the world wants to be on the receiving end of the line...

It's one thing if we are close friends, and you and I have an agreed exchange of email, but for those others, please don't add everyone you meet to your send-all lists!

I'm not the only one who hates this stuff. I hear complaints from a lot of my friends and family, who also ask, "WHY DO PEOPLE DO THIS?"