Enable Outlook 2010, 2007, 2003 Restricted Attachments in Seconds…

Wow, its been a while! – it would certainly seem that awkward things like work always gets in the way of providing content for either this site or some of the others that I am known to write for from time to time; but I have begun to make some changes to my schedule (and life) which will ultimately mean that I can post to my hearts content on this site – as well as maintaining a living in my day job! (more in this perhaps in a later post).

However, in the meantime I thought that I would provide you all with a new utility that I have concocted with my trusty copy of Visual Studio that allows for Administrators to quickly configure Outlook “Level1 Attachments” to bypass the default attachment filtering that Outlook has provided since 2003.

What are level 1 Attachments?

KB837388 provides a full summary but the following is pretty much sums up the functionality:

Microsoft Outlook will block attachments with file extensions that are considered to be “unsafe”.
This functionality is controlled from within the Windows Registry via the HKEY_CURRENT_USER\Software\Microsoft\Office\<Version>\Outlook\Security\Level1RemoveKey

Filenames that have extensions such as *.exe, *.ps1, *.vbs for example will not be accessible from within the Outlook client by default – unless they have been added to the “Level1Remove” key in the registry.

An example of the above is provided below;


Why have I done this?

Ok, its important to perhaps answer a couple of questions before I get into the “nitty gritty” (well at least the obvious questions that I can see being asked by a couple of people!).


Why have you created a tool that bypasses some inherent security risks in Outlook?


The intention for the tool is not to bypass security within Outlook, but to provide a simplified means for Administrators to allow access to certain attachments during troubleshooting or support.

There have been many occasions throughout my career (including a recent situation) where I have needed genuine access to certain file types that are blocked by default within Outlook (either on my machine or a users) – and I didn’t want to have to “ponce” around in Windows Registry to allow them – therefore a simple tool that allows you to quickly add the file extensions needed and access them – then remove them would have been really cool – so I decided to write one.

Besides – in Corporate Environments – many of these settings are controlled via the Admin Kit and Group Policy therefore it is unlikely that my tool would (or should!) work!


There are a few tools around that do this – why bother?


Yes, that is very true – but mine weighs in at 42KB – does not need installation, and is completely free of ad’s, banners etc. Plus its another tool that does something that would otherwise mean changing values manually within the Windows Registry – using my tool helps to take away an element of risk.

The Tool – Requirements and Download

The tool itself (which I have affectionately named “OutlookLevel1Remove” ~ creative bugger me) is written in C# and makes use of the .NET Framework 3.5.
The only versions of Outlook supported by the tool are:

  • Outlook 2010
  • Outlook 2007
  • Outlook 2003

Using the tool against lower versions of Outlook will not have any adverse affect on your installation – but will also not work Smile with tongue out


The tool is available for download from the following location:

levl1002[ Outlook Level 1 Remove Tool – 42KB ]

Using OutlookLevel1Remove.exe

You can download the tool from the above URL to your local machine – it does not require any installation.

Execute the application by double clicking on the “OutlookLevel1Remove.exe” file which will present you with the following Window:


From the bottom status bar – click on the arrow next to the Outlook icon to select the version of Outlook that you are running on the machine:


When you have chosen your Outlook version you will notice that the “Refresh” and “Remove All” buttons become available – you can use the “Refresh” button to view the current Level 1 exclusions in the Registry – and the “Remove All” button to remove them permanently:


If you would like to add an exclusion – in the text box under the “Add Level 1 Exceptions” area type in the file extension that you would like to allow (including the preceding “.” – e.g. .exe), and then click on the “Add” button – if you would like to add multiple values – separate each with a semi-colon:


The extensions that you have configured will then appear in the Existing Level 1 Entries Window – you can then restart Outlook for the changes to take effect:


That’s all you really need to know! – I hope that someone finds the tool useful – and of course, I always welcome feedback and suggestions!

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