RE: [Exim] ACL to ALLOW only mentioned attachments type and …

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Author: Dickenson, Steven
To: 'Chris Edwards', exim-users
Subject: RE: [Exim] ACL to ALLOW only mentioned attachments type and block *
Most Exchange admins (arguably mail admins most concerned with Windows
viruses) consider Martin Blackstone's list of danger to be rather complete.

Of course, it doesn't include archive files (Zip, Rar, etc), but does cover
just about everything that can be directly executed by Windows.

Steven Dickenson <sdickenson@???>
Network Administrator
The Key School, Annapolis Maryland

-----Original Message-----
From: Chris Edwards []
Sent: Friday, March 26, 2004 7:45 AM
To: exim-users@???
Subject: Re: [Exim] ACL to ALLOW only mentioned attachments type and block *

| > Can i write a ACL which allows only specified attachments type and
| > BLOCKS all *

| I'm wildly guessing here, as I haven't tried to see if this actually works
| with the way Exiscan hooks into the ACLs, but how about:

| deny message = Bad attachment
|      !demime = txt

| if you only wanted to allow attachments with a "txt" extension?

Interesting. Our management recently suggested a "default deny" policy
for file extensions. Quite tempting, considering the state of M$
I hate to think how many dangerous filetypes are not on our banned list.

Of course, outside of the M$ world these are arbitary file names. A unix
user might be mailing yesterday's results in a file called "results.thu"
and get blocked. Not really practical here.

Chris Edwards, Glasgow University Computing Service


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