How to trace whether spome valuable documents sent from office mail to hotmail / yahoo web based mails

Is there any software or using Linux Box, is there anyway to trace who
sent any mails to web based mails like hotmail and yahoo mail. mailny
some office documents can be sent to these web based mails. How to
trace these things, recently started training center, kept lot of docs
for the students, all these documents were collected by paid money. we
are allowing students to use these docs as part of training, but we
wanted to stop mails can sent to hotmail and yahoo, we provided e-mail
access for students on all these Linux systems, appreciated for any
idea, thanks in advance.

You can filter/block specific addresses emails with postfix.
either block the IP, or write a forwarding rule to route those
email addresses back to a mail account of yours, then you will know who
and when, and what.
If you are just looking for your docs, then adding a scanning filter for
those attachments would also work.
But if the person uses his own smtp service, you will need to scan all
port 25 traffic also.
Robert

On Sun, 03 Dec 2006 13:36:25 -0800, GS wrote:

> Is there any software or using Linux Box, is there anyway to trace who
> sent any mails to web based mails like hotmail and yahoo mail. mailny
> some office documents can be sent to these web based mails. How to
> trace these things, recently started training center, kept lot of docs
> for the students, all these documents were collected by paid money. we
> are allowing students to use these docs as part of training, but we
> wanted to stop mails can sent to hotmail and yahoo, we provided e-mail
> access for students on all these Linux systems, appreciated for any
> idea, thanks in advance.

On 2006-12-03, GS <(E-Mail Removed)> wrote:

> Is there any software or using Linux Box, is there anyway to trace who
> sent any mails to web based mails like hotmail and yahoo mail.

Set up a transparent proxy, e.g. "squid" though which all web traffic
must go to leave your network. The log files will show which machine
accessed what sites.

> we are allowing students to use these docs as part of training, but we
> wanted to stop mails can sent to hotmail and yahoo, we provided e-mail
> access for students on all these Linux systems, appreciated for any
> idea, thanks in advance.

Squid can also be configured to block access to sites.

--

John ((E-Mail Removed))