What's the etiquette on chain letters (e-mails)?

my closest friend always sends me emails that go, add your own whatever, in this case astrological sign, then it goes on to say this is really true, I saw how this worked on Chris Angel (!) and then it says if you don’t forward it to like 12 other people you will have a really bad morning and it will only get worse. All the people I know are at work and would get pissed If I sent them stuff like this, and I myself find it annoying. I looked at the list of all the people in the address line and assume they are at work, these people are adults! and some have really good jobs, I don’t get it? I replied “chainmails are a no-no” and now I feel bad-