Last reviewed on August 21, 2013   —  11 Comments

The Outlook E-Mail Security Update (included in Office 2000 Service Pack 2 and later versions) blocks access to .exe, .com and other “dangerous” files. See Attachment Security for a list of the affected file types. You cannot open these files from Outlook, nor can you use Outlook to save them to your system. If you try to forward a message containing an .exe file, Outlook does not include the attachment in the forwarded message.

blocked exe

With the rash of recent viruses using *.zip files to get past antivirus filters and bypass Outlook’s attachment block, you may want to add the zip extension to the Level1Remove key to force users to save zips to their hard drive before opening or block access to zip files completely by adding zip to the Level1Add key.

So what do you do when you receive an .exe file and must find a way to open it? There are several methods, depending on your version of Outlook.

Recent Outlook Versions | Import to Outlook Express | Outlook Web Access | Tools | More Information

Recent Outlook Versions

Outlook 2010, Outlook 2007, Outlook 2003, Outlook 2002 and Outlook 2000 SP3 (but not Outlook 98 or earlier Outlook 2000 versions) allow the user to use a registry key to open up access to blocked attachments. (Always make a backup before editing the registry.) To use this key:

  1. Run Regedit, and go to the appropriate key for your version of Outlook (see list below)
  2. Under that key, add a new string value named Level1Remove.
  3. For the value for Level1Remove, enter a semicolon-delimited list of file extensions. For example, entering this: .mdb;.url would unblock Microsoft Access files and Internet shortcuts. Note that the use of a leading dot was not previously required, however, new security patches may require it. If you are using “mdb;url” format and extensions are blocked, add a dot to each extension. Note also that there is no space between extensions.

Outlook 2013:

String: Level1Remove
Value format: .mdb;.url;

Outlook 2010:

String: Level1Remove
Value format: .mdb;.url;

Outlook 2007:

String: Level1Remove
Value format: .mdb;.url;

Outlook 2003:

String: Level1Remove
Value format: .mdb;.url;

Outlook 2002:

String: Level1Remove
Value format: .mdb;.url;

Outlook 2000 SP3:

String: Level1Remove
Value format: .mdb;.url;

If you are using this registry entry, a glance at Help | About Microsoft Outlook will show Security Mode: User Controlled above the license information.

To force users to save *.zip files to the hard drive before opening, add .zip to the extensions step 3. See Block Additional File Types in Outlook for more information.

If you prefer not to edit the registry directly, you can use one of the tools below to make the change; not all support both Outlook 2002 and 2000.

After applying this registry fix or using one of the tools, the user still has to save the attached file to a system drive before opening it. In effect, the fix rolls the attachment behavior back to Outlook 2000 SR-1, with its included Attachment Security Fix. An end-user cannot bypass this “save to disk” behavior and open the file directly from the mail message, though an Exchange administrator can.

Import to Outlook Express

The newest versions of Outlook Express block attachments by default. To retrieve attachments, click Forward and save the attachment from the message, then close. It can also be disabled in OE’s Tools | Options | Security dialog.

You can use either of the above methods to access .exe files from Outlook messages imported to OE. To make this process easier, consider creating a separate folder in Outlook to which you copy messages with attachments that you want to import. To import into OE, use OE’s File | Import command.

Outlook Web Access

If you work in a Microsoft Exchange Server environment where Outlook Web Access is deployed, you may be able to use OWA to open messages and get the attachments. Exchange Server 2000’s OWA has no attachment security, while Exchange 2003 added attachment security to OWA.


Advanced Security for Outlook

Use Advanced Security for Outlook to learn what programs are trying to access Outlook and permanently allow or deny access to the program and the next time it requests access, the action you choose will be automatically executed and Outlook Security will not annoy you with messages about trying to access e-mail addresses you have stored in Outlook. Freeware, available in English, German and Russian. Advanced Security is fully compatible with Windows 8 (32-bit and 64-bit editions) and Microsoft Office 2013 (32-bit editions only). The programs button is available on the ribbon in Outlook 2010 and Outlook 2013.

Attachment Options

COM add-in by Outlook MVP Ken Slovak that adds an Attachment Security Options page to the Tools, Options dialog in Outlook 2000 SP3 or higher to allow you to manage which file attachments are blocked. New version adds support for the .gadget extension for Outlook 2003 SP3 and Outlook 2007 SP1. It also adds detection for those SP levels. Shareware. Version 1.9.6

Attachment Security for Microsoft Outlook

"Outlook blocked access to the following potentially unsafe attachment ..." If you get this message when attempting to access an Outlook email attachment you'll want to install Attachment Security for Outlook; a free program for unlocking attachments blocked by Outlook. Attachment Security for Microsoft Outlook is a free and easy to use software program that allows you to open attachments blocked by Microsoft Outlook e-mail security.

CodeTwo Attach Unblocker

Use CodeTwo Attach Unblocker to configure Microsoft Outlook to allow the openig of the attachments blocked by default (for example, .exe, .url, .reg). The program is an Outlook extension; its settings are available at the property sheet in the Outlook options, which ensures quick and convenient editing. Supports all versions of Outlook, including Outlook 2010 64-bit

CodeTwo Outlook WarningDoctor

CodeTwo Outlook WarningDoctor removes the security warnings that appear when sending mail or performing other actions recognized by Microsoft as a "risky" (for example, when you try to read some data using the Outlook or CDO API #. Especially useful for designers of macros, Visual Basic, and programmers of other scripting languages that use the object model.Outlook 2000 and up, including Outlook 2010 64bit.

Outlook Attachment Enabler

Control what attachments Outlook has deemed to be unsafe and be free to open any attachment you like. You can also add to the default list of blocked attachment types. Controlling the safe and blocked attachments has never been easier. Includes the full and complete list of what Outlook will block by default. (Outlook 2000, XP, 2003 or greater)

Outlook Security Configurator

Free tool for setting up how Microsoft Outlook block (or not) e-mail attachments. Get rid of the message "Outlook blocked access to the following potentially unsafe attachments". Beta


We’ve heard of some other approaches:

  • Editing the Outllib.dll file with a hex editor to overwrite the extensions listed for “dangerous” files (e.g. the method used at Is there any way to work around the Outlook security update?)
  • If you installed Office 2000 Service Pack 2, substituting the Outllib.dll and Outllibr.dll files from Service Release 1.
  • For Office 2000 SP2, downloading the administrative version of SP2 and deleting the .msp file that contains the Outlook updates, then installing SP2.

However, these methods put Outlook into an unsupported, potentially unstable configuration, and we don’t recommend them. In particular, the last two ensure that you do not get any of the Outlook in Office 2000 SP2.


  1. james latimore says

    This Help page doesn't help. I wanted to know how to prevent the "security concern" messages from popping up again and again---even after the items of concerrn have been disabled.? I have to cancel them each time I go into my email. How do youget rid of those things?

    • Diane Poremsky says

      I'm not sure which dialog that is. Can you post the screenshot somewhere and post the url here or email me a screenshot? (diane at slipstick)

  2. Dale says

    I am unable to open any links in outlook it blocks everything says I have no access. What can I do to get this reversed. If I want to look at a job posting it will not let me access that job description

  3. Bernard says

    With Outlook 2003 (SP3) I get 'Outlook blocked access to the following potentially unsafe attachments...". This happens with .pdf files which I generated myself and attached to outgoing mail. Incoming .pdf attachments are not affected and open with a click, just not my own. I attach my invoices and receipts as PDFs and would like to review them before sending, but the security prevents this.
    I tried the standard Registry "fix" offered by Microsoft, but that just seemd to have the opposite effect.
    Any suggestions on how to turn this security warning off in outgoing mail?

    • Diane Poremsky says

      PDF's should not be blocked at all. Which registry fix did you try? Do not use Level1Add or Level1Remove keys. If you did, delete those keys.

  4. Doug Bennett says

    I tried your method of stopping outlook from blocking .com. Nothing even close. There must be many updates since your post. Thanks; God Bless you and yours.

    • Diane Poremsky says

      The Level1Remove method still works. You are talking about files ending in the .com extension? You need to add .com to the Level1Remove value. Links to .com websites are lnk or url extension.

  5. jorge says

    I tried your solution to unblock PDF attachments in a customer's computer but it didn't work still getting Attachment security warning and the attachment is removed. They still use windows xp and outlook 2003..

    • Diane Poremsky says

      Version wouldn't affect it, as long as you used the correct key for that version. (You might need to restart Outlook for it to take affect.)

      Try one of the addins - such as this one - - they set the same key but eliminate possible typos. If it still doesn't work, what antivirus/security software do you use?

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