Even if you allow others to read your work for free, you still own the copyright unless you transfer it directly through a contract. Unless that person wrote it, you can assume that the copyright belongs to someone else. Be very cautious about passing along articles, stories, jokes, etc., that someone else forwards to you. Just because the notice isn't there doesn't mean it doesn't apply. Copyright is established by the very fact that someone wrote the material, NOT by whether or not a notice has been posted.
Authors appreciate having their work passed on and shared.
No, they don't. Of course authors are glad that their work is appreciated - but no one appreciates having their work passed on without permission. The best way to be helpful is to pass along the URL to a useful article.