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Outlook tries to protect you from opening certain types of attachments, even if you know they're safe. A registry change puts you back in control.

How do I force Outlook to open "potentially unsafe attachments" that I know are ok?

As discussed in an earlier article Outlook tries to protect you from viruses by blocking access to files which have certain extensions like ".exe" for example, because they could carry a virus and infect your machine.

Watch The Video

Click the video above for a one minute video showing you how to add the Level1Remove entry to your registry as described in this article. (Windows Media 9 format, 654,896 bytes.)

I'd Like Your Comments: let me know if you find the video above useful, or if you have suggestions to make this technique more helpfull. Thanks!

Microsoft's official recommendation is that you have whomever sent you the file rename or zip it and send it again. And to be honest that's probably still the safest approach overall.

However that's just not an option sometimes. Fortunately there is a registry setting you can add that will instruct outlook to treat extensions that you specify as safe.

Before we go mucking about in the registry I'll caution you that the registry is a critical component of the operating system, and it's possible to render your system totally useless if you make the wrong changes. Microsoft provides instructions for backing up the registry here.

That having been said, the steps I'm about to outline are relatively simple if you follow along carefully.

  • Start the registry editor by pressing the Start button, Run, typing regedit and pressing OK.
  • In Registry Editor, expand, in turn:
        HKEY_CURRENT_USER
          Software
            Microsoft
              Office
                11.0        (Office 2003. For Office XP, expand "10.0")
                  Outlook
    
    Expand each entry by clicking on the boxed plus sign to it's left. If that's a boxed minus sign then it's already expanded.
  • Now click on the Security entry.
  • On Registry Editor's menu bar select Edit, New, and String Value.
  • Replace the default name of "New Value #1" with "Level1Remove".
  • Right-click on Level1Remove and select Modify.
  • Enter the list of file extensions that you want to gain access to. The list is semi-colon separated. For example if you wanted to allow access to both ".url" and ".exe" files then you would enter ".url;.exe".
  • Exit Registry Editor and you're done. You may need to restart Outlook if it was running while you were doing this.

Remember: once you have enabled access to a particular file type, you are assuming responsibility for making sure that an attachment is safe before you open or run it.

Article C1864 - November 23, 2003 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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Recent Comments
35 Comments
Bob
December 4, 2008 9:45 AM

Your Tip works :) .. Thank you

Jeff
January 20, 2010 10:58 AM

Thank you for this clear and helpful tip. I was hoping it would apply retroactively to an email already in my inbox but apparently not. Also, I was surprised that I couldnt forward the message to another address and open the .pst file but I guess that makes sense as my server blocked it up front?

Yngve
May 29, 2010 2:16 AM

Thanks.
This solved my problem.
However .pdf files where not listed by outlook as dangerous files. Still my system kept blocking them until I manually listed .pdf with Level1Remove.

I will never cease to be amazed by all the silly and stupid things M$ software does witout requesting permission or atleast informing the user about.

Michael
December 1, 2010 12:00 PM

THANK YOU! How insane that there isn't a bit in the Outlook GUI somewhere to toggle this ...mmmm... "feature"! You da man, Leo.

G
March 11, 2011 6:28 AM

this was written fro 2003 or xp versions of office but it works for 2007 and probably 2010. 2007 is 12 in the registry and my guess is 2010 is 13.
Helpful Tip don't put quotes in the extentions list you type in not ".url;.exe" but url;.exe