How to stop Outlook 2010 from blocking potentially unsafe attachments
From Tech-Wiki
More actions
Historical Outlook 2010 registry policy for changing blocked attachment extensions.
Legacy / version-specific guidance
Outlook 2010 is out of support. Keep this only for a legacy estate; current Microsoft 365/Outlook environments should use supported attachment and security controls.
Validation status
Reviewed during the Tech-Wiki Wave 3 migration on 27 September 2026. The historical procedure is retained for engineers supporting older estates, but is not presented as the default approach for a new deployment.
Weakens attachment protection
Unblocking executable or script attachment types increases malware risk. Prefer controlled file-transfer methods.
Historical procedure
Add the file extension you wish to unblock to the following Windows registry key:
fileextensionsremovelevel1 (and maybe 2) under HKCU\software\policies\microsoft\office\14.0\outlook\security
Entries should be separated by a “;”.
Restart Outlook once done.