HOW-TO: Unblock Microsoft Outlook "Unsafe" Attachments

There are folks who send you mails disguised from persons you might know, but little do you know of the malicious content they send as attachment. In the name of security, Microsoft has started to put in place measures so that the average joe will not be able to potentially stumble on attachments that auto-execute when clicked. That is a good practice. And while that is not bad, they should also advise the end-user how to bypass such security when necessary.

This is not the case, however. Microsoft Outlook will block registry files, executable files, javascript files, scripts and other files that are potentially hazardous. This is a blanket rule that doesn't have an exception. So whenever you get sent an attachment that fits the rule, even if you are sure it will not cause any harm it gets blocked. And you will be getting a window just like below (from Microsoft Outlook 2007).

Error message will look like below (filename may differ):

Outlook blocked access to the following potentially unsafe attachments: attachment_filename.exe

How then do you access the attachment when you are sure of the sender and the attachment is confirmed to be safe? This is another classic scenario of functionality versus security. Follow the procedure below to be able to access the blocked attachment.

If Microsoft Outlook is open, close it. Then open the registry editor and browse to the below registry branch.

Locate the following key(s) depending on the version of Microsoft Outlook you have:
* Outlook 2000 [HKEY_CURRENT_USER\Software\Microsoft\Office\9.0\Outlook\Security]
* Outlook 2002 [HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\Outlook\Security]
* Outlook 2003 [HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Security]
* Outlook 2007 [HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Security]
* Outlook 2010 [HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Security]

Look for the key "Level1Remove". If it does not exist create it as a string data type. Separate each file extension entry with semi-colons. Make sure to follow the syntax as this is case sensitive. As I use my email to archive scripts, I usually send a mail to myself with the script attached. So this is how it looks on my registry (see below).

After making the necessary changes above, launch Microsoft Outlook and re-open the email with the attachment(s) and you can now access the attachment.

There you go folks.. Another tweak to access blocked attachments. As a security measure especially on shared computers, once you add this and access the required attachment remove the registry entry Level1Remove. Just add it when you require access to blocked attachments in the future.