SMTP/POP Transparent Proxy

["Henrique Moura" <henriquemoura () hotmail com>]

Hi,


First of all, sorry for my bad english.

I manage several LAN´s each one connects to internet by broadband ISP
(except HQ). Our employees travel a lot, so one day John is at "Office 01",
the other day he is at "Office 02". His e-mails are at "ISP 1" (our e-mail
server is outsourced) and he also has his personal email at Yahoo or other.

What I want is to protect my LANs from virus, so I´m looking for a
transparent e-mail proxy, then when John is at "Office 01" and opens his
outlook express and it tries to connect to the ISPs that are configured in
it, the message flow passes through a firewall (a linux box I already have),
the firewall captures these packets, sends them to the proxy that checks for
spam and viruses and, finally, sends a clean message to ISP email server
configured for Johns account at his Outlook Express. I don´t want to rely
the antivirus installed on his notebook. And if he move to another office
this scheme still works.

I know how to make a bastion host with postfix (or sendmail or exim) to
protect my internal email server, but that´s not what I want.

Can anyone help me?