I recommend you use "BCC" (blind carbon copy)option of addressing email when forwarding or replying to an email. The addresses you put on the forward/reply using this option will not be seen by the recipients of your email AND will not be included on any email your recipients forward.
We know our friends, but we don't know their friends or their friends friends and so on. I suspect forwarded emails loaded with valuable legitimate email ids are prized by scammers.