I notice SPAM has made its way to our group messages.
It is easy to spot here or even in your mailbox. SPAM usually says "no subject" in the subject line.
My sister inadvertantly opened one of these messages. Later, she found that all of her email contacts (including me) received an email from her that she never sent. I didn't open it (since I saw the "no subject", which can be a tipoff) but later found out that those who did got a virus on their computer and major damages.
Therefore, in reading messages here and elsewhere, don't click "next message" unless you know it is from a valid sender.