I’m cautious opening email attachments, even from people I know. I got an email from one of my computer repair clients last week that he sends out to a group of recipients regarding his area of expertise. These are usually sent out bi-weekly or monthly – I don’t remember. Usually, it’s information only in the body of the email, but this time a PDF attachment was included. PDF stands for Portable Document Format and is the most widely used file type for sharing data. But it can also carry a payload or be something besides a harmless document that it’s supposed to be. That’s why I usually won’t open attachments on my main smartphone or my business computer which has my accounting program for my computer consulting business. And my smartphone and computers all have security programs on them. If I open attachments, it’s with a Linux computer of which I have several. Linux is much safer for opening unknown email messages and attachments because it won’t let unknown processes execute with admin or root privileges. For my Microsoft Windows computers I usually have Comodo Internet Security installed on them. Comodo has a secure Sandbox built-in and you can run any program in a virtual environment which isolates it from the operating system. Since all my email is web-based, I can run my web browsers in a Comodo sandbox to protect my computer from malicious email. If you are unsure about an email message and you need to read it, open it on an unimportant device or computer – don’t open it on a computer which has your important programs and files on it. Another protection stategy would be to call the email sender to verify they really sent you something and if it was business-related.