[Mimedefang] message/partial

[Aleksandar Milivojevic]

Carlton Thomas wrote:
> We advise our clients to send multi-part messages to overcome the
> 10 meg limit we impose on a single message. We understand that this
> can allow viruses to slip through our defences, but we had to impose
> a limit and we had to find some way of allowing messages larger than
> that limit to be sent.

Huh.  Yeah, the problem sounds familiar.  Long time ago, users would 
upload 100kb file on FTP server and send email where the file is. 
Today, users would click "attach" icon and select 1GB file without 
thinking twice.  It's like going to Rona or Home Depot web site, buying 
everything you need to build new house online (from concrete for 
foundations to roof shingles), and selecting FedEx or UPS as shipping 
method.  They'll do the job, but they are far from optimal.  Just as the 
E-mail servers and clients will do the job of transferring 1GB file, but 
they are far from optimal solution for transferring the file of such size.

> One possible solution to handle viruses in these types of messages is
> to create a mimedefang filter which recognises the first part of a
> multipart message and impose a minimum size limit on that part.
> This is consistent with the assumption that most messages which
> contain viruses tend to be small. Mimedefang currently allows the
> admin to make that assumption and to only scan messages below a
> certain size.
> 
> Would this be a suitable compromise, and is it possible to implement
> it using in a mimedefang filter?

If you are willing to live with the risks, yes it is possible.

-- 
Aleksandar Milivojevic <amilivojevic at pbl.ca>    Pollard Banknote Limited
Systems Administrator                           1499 Buffalo Place
Tel: (204) 474-2323 ext 276                     Winnipeg, MB  R3T 1L7