delphij's Chaos


21 Jan 2005

How to disable Outlook's level 1 attachment blocking feature

I’d say I really dislike this feature, it always prevent me from being able to receive attachments and does not actually block virii since I have some carefully designed security mechanisms installed on my computer.

Of course someone may say “Outlook sucks, don’t use it!” but I won’t say that. Outlook is a great product that is very safe if you have configured it *CORRECTLY*. The feature of the attachment blocking, while may be useful for not experienced users, will harm users that is experienced and is highly security-aware when communicating with non-experienced folks.

You are on your own risk if you do the following change. This change may cause severe security problem if you are not actually security aware.

In order to work around the issue, one can tweak his or her registry:


Add a REG_SZ here, like:


Assign the following value:


Of course there are other file types that is blocked, you can add them to Level1Remove as well, but hey, it won’t be good for your security :-)

Additionally, you should add the above level under the name Level2Add to ensure that you get warnings when opening these attachments.

References: Microsoft KB Q318515