Unblock or Allow Microsoft Access Databases and Other File Attachments in Microsoft Outlook Emails

Is Microsoft Outlook preventing you from receiving files people are trying to send to you? Adding a registry value bypasses this security feature.

All versions of Outlook later than Outlook 2000 SP2 disallow you from opening certain file types, such as .mdb, .adp, .exe, .hlp, and more. In some regards, this is a great security feature, but there are times when you need to receive these files as attachments. It’s best if the sender can send a Zip file, but if not, you can create a registry key to un-block the desired file types.

Use extreme caution when modifying the registry.
Changes to your registry can render your entire system unusable.

1. Open the Registry Editor (choose Run from the Windows Start menu, type “Regedit”, and click [OK]).
2. Locate My Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\Version\Outlook\Security (where Version is your version number of Outlook:
   • 9.0 for Outlook 2000
   • 10.0 for Outlook 2002
   • 11.0 for Outlook 2003
   • 12.0 for Outlook 2007
   • 14.0 for Outlook 2010
   • 15.0 for Outlook 2013
   • 16.0 for Outlook 2016
3. In the Security key, add a String value named “Level1Remove” (without the quotes).
4. Modify the String value, and add the list of file types to allow Outlook to open (separated by semicolons). For example: ".mdb;.adp;.mde;.ade" (without the quotes).

Note: Microsoft recommends that you enable only the file types that you require. If you rarely receive a particular file type, Microsoft recommends that you give Outlook temporary access to the file type, then reconfigure Outlook to block the file type by undoing the changes to registry.

See Microsoft's page, "Outlook blocked access to the following potentially unsafe attachments" message in Outlook for more information.