MailScanner gateway using sendmail

You want to run a MailScanner using sendmail and you only want it to relay to an other server (Exchange, Domino, Groupwise...). Here is the best way to do it:

• Set your MailScanner box(es) to be MX(s) for the domain (i.e. available to the outside world), running MailScanner.
• A Windows box running Exchange on an IP address not available to the outside world (in our case 192.168.10.5)
• On the MailScanner box, there is a file called /etc/mail/mailertable. It put the following line in it:

ourdomain.co.uk smtp:[192.168.10.5]

(The brackets tell sendmail to bypass DNS resolution.)

• Add the domain name to /etc/mail/relay-domains

This tells sendmail to push the mail off to the Exchange server, but crucially, it does this AFTER MailScanner has done its work.

The user then picks up their now cleaned mail from Exchange. You should also configure your exchange server so that it uses your MailScanner server for Smart Host (don’t forget to create rulesets accordingly.