by June 8, 2006 0 comments

Mail attachment stripping-what is so great about it, you
might ask, because that’s what this project was about? But you would sing a
different tune had you been the CIO of an organization that handles about 40
million email messages a month, amounting to 2.2 TB. Even if every message were
around 50 kB, the amount of bandwidth required to handle the load is not funny.
Any amount of WAN bandwidth optimization would not be enough. That’s exactly
the problem ICICI Bank faced with its messaging system after they centralized
their email system. They were having email with an average size of 45 kB, out of
which 25 kB was due to various attachments. The scene became even worse when one
mail was CCed to multiple people with the same attachment. So when a mail comes
in with a huge attachment, a user has no other choice but to download it, which
also led to choking of ICICI’s WAN links.  


High WAN bandwidth usage, slow mail server access, excessive e-mail attachments

Strip mail attachments and store them centrally; accessed through URL in the original mail


Pravir Vohra, Senior GM, RTG and TMG team along with Gajshield Security Solutions 


Linux, Perl, C, Apache, Sendmail
Pravir Vohra, 
Sr General Manager

That’s when Pravir Vohra, Senior GM of ICICI’s
technology management team thought of putting in a solution that would strip all
mails of their attachments and place them in a separate directory on the mail
server itself, and place a URL pointing to its location in the email. So if a
user sitting in


sent out an email with an attachment to other users across the country, then
its attachment was first stripped by the mail server and placed in a separate
directory. All the recipients received the mail with a URL pointing to the
attachment. They did face some resistance from the users initially, but it
didn’t last for long, because mail downloads became faster all of a sudden.
Even top management didn’t require much convincing because this simple
solution saved close to 30% of the WAN bandwidth and an equal amount in storage.

The solution had many other indirect benefits also. For
one, as the users’ mailboxes stopped becoming as full, the mail servers’
performance improved. In fact, even the performance of anti-virus servers
improved, because they weren’t spending time scanning so many incoming
attachments. Likewise, it also reduced the time to do mail server backups. So in
all, a simple solution like this managed to make the whole system more
effective. Users can now download their attachments at their own convenience,
possibly during off-peak hours so that the network bandwidth doesn’t get
choked. Truly innovative!

The best part about the solution is that it’s only been
implemented for ICICI’s internal users. Mails to or from external users are
not stripped. This places another condition on the system that internal users
can access their attachments only if they’re connected to ICICI’s enterprise

Pravir has worked out the solution to this as well. The
mail servers and the attachments directory are accessible to users over a VPN
connection as well. The mail-stripping program has been implemented on Linux and
can work with both Sendmail and MS Exchange. In Linux mail servers, the program
strips the attachments of all outgoing mail, while in Exchange, it does it for
incoming ones.

ICICI has done it on a Gajshield Linux mail server and
integrated the attachment stripping program with Sendmail using a Sendmail API
called milter. The way it works is fairly simple. The program checks the domain
name of the recipients. The attachments are stripped only if it’s going to the
local domain. Mails marked to Internet domains are allowed to pass as is. The
program has been developed in C. The program affixes a date, time and process ID
to each attachment so that it can easily be identified.

The good thing here is that other than the cost for
development of this code, there was no cost for the rest of the software. In
fact, the overall cost of implementing this solution was peanuts, as it was
deployed on top of the existing messaging hardware. There was no additional
manpower cost either, as there’s hardly any management required for the
system. The existing IT administration team can handle it. 

The project only took three months for development,
testing, and final deployment. Currently, it’s  serving 35,000 users at

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