By the way, there are several recent reports of both Mac and Linux systems now being affected by those users using the direct open option to open E-mail attachments. Virus authors are getting smarter about holes or knowledge gaps that millions of computer users have if they've never taken formal computer classes.Thanks Neemobeer. I'll look at this.
Well, it turns out you really don't WANT to set that option to "Open" anyway, as that bypasses all your AV security as well as your Firewall protections and can result in you getting one of the really nasty RANSOMWARE viruses floating around out there now such as NEMUCOD or CRYPTOLOCKER. These little nasties will require you to cough up $250-$4000 US in bitcoin to the virus authors to unlock access to your computer or all the files in your computer will be encrypted.
In the Tech community, we've been trying to get the major E-mail providers to completely REMOVE this option from all their E-mail client apps (Outlook.com, Outlook.com, W10 Mail, Thunderbird, etc.). I've been trying to teach students for 20+ years that they should NEVER use this option for the very reason that it temporarily disables your security programs from scanning attachments which contain dangerous Script or Worm viruses that you are effectively "letting loose" on your computer. In beginning Computer Classes where we teach adult learners *especially seniors* how to use E-mail, this is one of the first safety measures we teach them. So, you really need to be very careful on changing this option-yes, it can be changed, but you still have to know about never opening E-mail attachments directly.
FYI.
Hope that proves helpful to you.
<<<BIGBEARJEDI>>>
NEMUCOD locked up his system and encrypted all his files and demanded a $257 ransom to unlock 20 years worth of his business and personal files! He went through 2 or 3 other Computer Techs who were at a complete loss to fix this and they just told him to pay the Ransom.
He finally got a hold of me, and after spending a month solid on it; I was finally able to unlock all his files. The authors of this virus count on people like him who try to learn how to use computers on their own, but never really study it's use in detail in classes. To them, the Computer is just like a fancy toaster. They don't care how it works, nor do they care to learn about the high risk threats out on the Internet. They just figure they'll hear about it eventually--and in this case, he did--but it was almost too late for him. If I hadn't come along, he'd have lost 20 years of his business and personal files, and he was going to just buy a new computer and start from scratch. Good thought though to keep from downloading bad stuff via questionable websites you visit and download from; but doesn't apply to E-mail worm virus. The infection morphology is much more sophisticated than what you are currently doing for protection is capable of protecting you from. Anyone else reading this might assume that what you are doing is adequate protection--and that's just not the case--as my little story about my Customer getting hit illustrates so well. 
