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.
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.
FYI.
Hope that proves helpful to you.
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