Setting up an internal mail filter

[Frank DiPrete]

On Mon, 2005-07-18 at 11:32 -0400, Jeff O'Brien wrote:
> First post to gnhlug....thanks ahead of time
> 
> I have a linux server (firewall(netfilter), gateway, mail(sendmail), 
> internal dns) with 1 static IP(MX record too), another linux server that 
> I want to act as mail filtering box(SA/clam-AV, etc..) on the internal 
> side of the firewall (both WBEL3rc1).
> 
> Is there a way to have mail that comes in to the external linux mail 
> server to be sent off to the internal mail server for filtering then 
> back to the mail server where end users can then get their mail to avoid 
> reconfiguring each client and without causing mail loops? 
> 
> -The first step would be to get the mail from the ext-mail server to the 
> internal filter.
> would I use a procmail rule, sendmail mailertable or firewall rule? 
> -have mail accepted on filter box
> -filter and score mail and send back to ext-mail server(which all 
> clients are config'd to, or  change internal dns records for mail to 
> point to filterbox instead of ext-mail server)
> 
> any suggestions and help are more than welcome  :-)
> 

um - better to set the external IP of the fw as the mx record then
filter/forward to your internal server.

things to look into:
sendmail - configured as a gateway
spamassassin-milter
clamav-milter
all above run as daemons