How do we know that a message in spam inbox is a fraud or just considered as a spam if we did not open it?

In just a week I received email in spam inbox 3 to 5 mails but there are email sent to spam inbox from our friends. how do we know an email in spam inbox is not a spam and just considered as a spam by the email server?|||I agree with the one above me. Just read it to find out, those spam inboxes just figure it's a spam for some very very odd reason. I mean like why would your friends send you a spam. I got one the other day that was a spam, but the title was like buy a rainbow unicorn, so i knew :) Hope I helped :)|||Usually your email program or webmail will allow you to read the emails without loading any images etc. so it is safe. As an added precaution always add people who you frequently receive mail from to your contacts and know that any unsolicited email can almost always be ignored.|||The best way is to read it.|||Spam is in the eye of the beholder. Maybe you really do want to buy viagra online





Antispam filters use various different rules. With some systems, you can report messages as spam or not-spam and it will learn what your preferences are, e.g. recognize your friend's addresses, or see that you like mail about travel opportunities.





Sometimes your friends get targetted by profiling. E.g. If your friend lives in Nigeria, a US system may say "100% of all messages I've seen so far from Nigeria are spam, so chances are this one is, too"





If you look at the open-source SpamAssassin, you can see exactly the rules that some filters use. Things like "title is all caps", "sent directly from a home PC", "uses the word viagra" all get points, and if the total goes over 5, it gets flagged.