How can you tell if an email attachment is safe to open?

Beware of email attachments, which can prove malicious. — AFP Relaxnews

One basic rule of the Internet is that you should never open an email attachment unless you’re sure it’s not a corrupt or infected file. And there are a few basic steps you can follow to avoid falling into this kind of trap.

First of all, never open unexpected or unsolicited attachments, especially if they come from unknown contacts. Clicking on a corrupt attachment – which can take the form of an image, video, text file or spreadsheet – can unwittingly launch malware on your device, with the risk of compromising the data it contains.