Over the last few weeks many people have been reporting unwanted Calendar invites, usually looking like junk email with a sales pitch and links. It is difficult to get rid of these invites without notifying the sender that you either declined or accepted it. But there is a method to quietly delete the invite. A better solution is to switch to email notifications of Calendar invites until Apple fixes the problem.
The best way to protect yourself against online scams is to learn about them. Here are three web sites that report scams. By browsing these sites a little each week, you will become knowledgable about these scams and learn to recognize when someone is trying to pull one on you.
You can use the Keychain Access app on your Mac to create secure random passwords for things that are not necessarily online. For instance, you can create random ATM pins or passwords for apps and other services. You can also store these passwords in your Keychain so you have a backup in a secure place in case you forget the password later on. Check out my book The Practical Guide to Mac Security at http://macmost.com/j-macsecurity