Outlook by default blocks certain attachments (file-types) from being viewed for security reasons. Once blocked the file cannot be 'un-quarantined' and it can be more useful to disable the blocking at the client-level and establish filtering at another level.

To disable blocking on a per-extension basis:

Locate the following registry key, where

is your version of Outlook: `    [HKEY_CURRENT_USER\\Software\\Microsoft\\Office\\``\\Outlook\\Security]` Create a new string key called \"Level1Remove\" and add the extnsion(s) you wish to allow; seperating them with commas. Outlook will need to be restarted for the changes made to take effect. ### See Also [Attachments blocked by Outlook](http://office.microsoft.com/en-us/outlook/HP030850041033.aspx) [Registry](Registry "wikilink") [Category:Outlook](Category:Outlook "wikilink")