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Attachment blocking in Exchange/Outlook

Bianca Rohland
Occasional Visitor

Attachment blocking in Exchange/Outlook

We are currently running Exchange 5.5 and Outlook 2000 on a Windows NT Server. Due to the security "upgrades" in Outlook 2000, all executable files are being blocked at the sender as well as the recipient. What this means is that we cant even send executable file types (including MS Office files) internally. Im looking for some control over this. So far all that Ive found is a white paper that involves setting up a public form to define the security. What the white paper doesnt mention is that the process is applied to the current user and you must be an administrator to apply it (an administrator cannot set it up for someone else due to the nature of the process). Now, I have seen vague references in Outlook help files that say that the Outlook rules can be managed from the Exchange server but Ive looked all through my 5.5 server and see no such option. Im wondering if it isnt referring to Exchange 2000. If anyone can offer some insight, I would appreciate it.

5 REPLIES
Jon Finley
Honored Contributor

Re: Attachment blocking in Exchange/Outlook

Using a hex editor, OUTLLIB.DLL can be edited (make a backup first) to remove the references to the file extentions you want to allow.

It's VERY important to NOT change the file size though, so whatever extentions you take out, need to be replaced with 0x20 characters

(verify this from within the dll file with the hex editor - It's been awhile since I looked at this)


Jon
"Do or do not. There is no try!" - Yoda
Alberto Rodriguez_1
Valued Contributor

Re: Attachment blocking in Exchange/Outlook

Bianca,

As a workaround, you might want to try using a utility called Winzip, its available at www.winzip.com as as I recall it is a free utility. It allows you to compress the files you are working with into .zip files of which Outlook and Exchange allow. The only caveat however, is to have the same file compression utility, or something that handles files with .zip extensions, on the client machine, whereby they can decompress the file at will.

Good luck,
Albert
To err is human, forgiveness devine
michael brooks_1
Occasional Visitor

Re: Attachment blocking in Exchange/Outlook

you can also check out the attached document which deatils how to handle this situation.
David L. Largent
Occasional Advisor

Re: Attachment blocking in Exchange/Outlook

I'm having a problem reading the attachment. Any suggestions?
Jon Finley
Honored Contributor

Re: Attachment blocking in Exchange/Outlook

Bianca,

Your choices are as follows:

1. rename or zip-up the files that are blocked to get around the security patch.

2. Edit the .dll file as suggested earlier to "remove" the extension from being blocked.


The registry fix mentioned only works with Outlook 2002, and NOT Outlook 2000.

BTW - I went back into the .dll, and any extentions removed need to be padded with '00'.

I've edited the OUTLLIB.DLL file, and am no longer blocked from sending or receiving .exe files and others.


Jon
"Do or do not. There is no try!" - Yoda