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Blocked Attachments in Microsoft Oulook

written by: Bruce Tyson•edited by: Bill Fulks•updated: 5/19/2011

When you get an "Outlook blocked access to the following potentially unsafe attachments," what does that mean? The problem may seem frustrating, keeping you from important files that are needed for work, but we can help. Read more about it here.

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    About Attachment Security

    Microsoft tries to help keep computers safe, but sometimes its efforts cause unintended headaches during a typical work day. Attachment security in Outlook is just one example of a feature that is meant to help, yet causes untold frustration for workers trying to get their jobs done. The truth is that attachment security is an essential feature that helps keep computers and networks safe.

    Years ago, hackers learned how to execute malicious code on a computer by having a user double-click on email attachments. Unsuspecting users would unleash all sorts of viruses, worms and bots, leaving IT personnel scrambling to fix the problem.

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    Dealing with Blocked Attachments in Outlook


    The first thing to recognize about the unsafe attachment system in Outlook is that the program will not allow users to do anything with the attachment. You can't save it, print it, open it or even delete it, making few options available for the recipient.

    What you as a user do about the attachment problem may depend on (1) how well you know the sender, (2) how often you get attachments you can't open, (3) how well you know your Exchange administrator (if applicable), and (4) how willing you are to mess with your computer's registry. Let's go through the options and then you can choose.

    1. Ask the sender to send the file in a compressed format.

    If someone must send you an executable file or a script, ask them to zip it first. This will produce an attachment with the .zip, .rar, etc. extension that Outlook will allow you to save. If the sender does not know how to zip a file, see if you can get her to rename it with an underscore as the last character. For example, if they were sending virus.exe to you, ask them to rename it as virsu.ex_.

    2. See if you can download the file from the sender's FTP site.

    Users who are somewhat tech-savvy could ask the sender of a blocked attachment to allow you to download it from their FTP server. Of course, not everyone has access to an FTP server and some people might not even know what an FTP server is, so this may not always work.

    Senders can always try to upload the attachment to file sharing services like Rapidshare or the now-defunct and send you the link in email. Again, this method represents a possibly significant technical hurdle, so it might not work out.


    3. Chat with your Microsoft Exchange administrator

    If your corporate email is managed on an Exchange Server, check with your IT department to see if they will agree to allow you tor receive files that are currently blocked. If you are on good terms with them, they might give you a break and change your account to allow the files through. Of course, this won't help if you are using Outlook with another type of email account such as POP.

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    4. Change your system's registry.

    Granted, some people should never even think about meddling in their system registry, but if you've used Regedit before and want to give this one a try, go for it!

    To get your email attachments to sail straight into your inbox, just a few changes are necessary.

    • Open Regedit. To do this, click the Windows start button and type "Regedit" into the search box and then press <Enter>.
    • Next, browse to the registry key, HKEY_CURRENT_USER\Software\Microsoft\Office\xx.0\Outlook\Security, where XX can be 9, 10,11,12, or 14. This depends on which version of Outlook you are using (2000, 2002, 2003, 2007, 2010 respectively). Hint: If you've had your computer for a while, you may have more than one of these registry entries. Please choose the one that matches the version of Outlook you are currently using.
    • Now, right click in the right hand panel and then click "New" and then choose "String Value."
    • Now type "Level1Remove" into the "Name" field and then press <Enter>.
    • Next, right click on "Level1Remove" and then choose "Modify from the context menu.
    • In the "Edit String" window, type in the file extensions of the attachments you wish to receive. For example, type in .exe;.com;.js, putting a semicolon between each file type.
    • Now, close Regedit and restart your computer. When you re-start Microsoft Outlook, you should be able to open attachments of the file types you defined in the system registry.
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    Outlook Tools

    As an alternative to manual registry changes, users could try a free Outlook utility called "Outlook Tools." This program provides a graphical interface for allowing or blocking Outlook attachments. After downloading and installing the program, click "Outlook Tools" from your start menu. attach005 

    In the Outlook Tools window, click the "Blocked Attachments" tab. In the window, check the file types you wish to allow Outlook to open and then click the "Save" button. When the confirmation box appears, click "OK" and then restart Outlook. Your attachments should now be accessible.