Outlook refuses to open certain file types received in an email. There are two level: Level 1 files cannot be accessed by the user, and level 2 files must be saved to disk before they can be opened.
InfoPath has a similar restriction: File with specific extensions cannot be attached to a formular. In fact, the InfoPath model stacks on top of the Outlook restriction list. To unblock an extension for InfoPath formulars, it must be unblocked both, in Outlook and InfoPath.
To unblock an extension in InfoPath, follow these steps:
- Unblock the extension in Outlook (see Regain access to blocked atachments in Outlook on how to do this).
- Open the registry editor
- If you are using InfoPath 2003, navigate to the key HKEY_CURRENT_USER\Sofware\Microsoft\Office\11.0\InfoPath\Security. If you are using InfoPat 2007, navigate to the key HKEY_CURRENT_USER\Sofware\Microsoft\Office\12.0\InfoPath\Security.
- If it does not exist, create a string value named UnsafeFileTypesRemove.
- Open the values and enter a semicolon delimited list of extensions (e.g. chm;msi;exe)
- Close the registry editor.
The new filetypes can be added to a form the next time InfoPath is restarted.