By default, Microsoft Outlook blocks executeable files (.exe, .bat and .cmd). To unblock executeable files, you need to change the Attachment Security Mode in Outlook. To change the Attachment Security mode, you need to make the following registry change (depending on your version of Outlook):
- Close Outlook
- Press Start -> Run and type regedit
- Depending on your version of Outlook, navigate to the following key:
- Outlook 2000:
- Outlook 2002:
- Outlook 2003:
- Outlook 2007:
- Outlook 2010:
- Oulook 2013:
- Outlook 2000:
- Right click the key and click New-> String Value. Name the value Level1Remove (It’s case sensitive!)
- Edit the newly created value and enter the file extension of the type of attachment you would like to unblock in Outlook (including the dot). For example, to change the Attachment Security Mode to unblock executable attachments and batch files, type:
- Click OK and close the registry editor
The Attachment Security Mode should now be set to allow Outlook to open executable and batch files. Be warned that Outlook blocks these attachments for your security. Make sure that you have a reliable spam filter and antivirus software enabled before unblocking executable attachments in Outlook!
Other Ways To Change The Attachment Security Mode
I haven’t tried it, but I imagine you could also change the Attachment Security Mode with the Outlook GPO by downloading the admx files. Failing that, you could make an admx file with the above registry information.
Here is a full list of attachments blocked by Outlook, as published by Microsoft.