Opening blocked attachments in Outlook

by Shijaz Abdulla on 09.01.2008 at 10:23

Some file extensions are blocked by Microsoft Outlook for the potential damage that they may cause. File types blocked include EXE, COM, MDB and many others.

Outlook displays a message that it has blocked the attachment:


Sometimes it becomes necessary to “unblock” a particular file extension. One of the most common requests is to unblock Access database files (*.mdb). Let’s see how this can be done:

  1. On the desktop running Outlook, open Registry Editor.
  2. Navigate to HKEY_CURRENT_USERSoftwareMicrosoftOfficexx.x OutlookSecurity where xx.x is your Outlook version number (9.0, 10.0, or 11.0)
  3. Add a new string named Level1Remove
  4. Add value to this string with all the extensions that you want to unblock, separated by a semicolon. (For example: .mdb;.url ) Remember to put the dot before the extension.

It should, however, be kept in mind that unblocking a particular file type introduces new risk, as the user can also receive a malicious file of the same type from another user or the internet and he/she might inadvertently open it.

For Outlook 2007, you need to insert the string in the following key HKEY_CURRENT_USERSoftwarePoliciesMicrosoftOffice12.0OutlookSecurity. If the key path doesn’t exist, you can create it.

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One Response to Opening blocked attachments in Outlook

  1. naj says:

    Nice article really helpfull

    Najeeb
    Bahrain

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