This patch allows Exim mail server to use multiple interfaces/ips for outgoing smtp connections. It allows the system administrator to set up an ip pool with the desired ips and then qmail will rotate trough the list of ips for each outgoing email. The ip pool is very easy to manage as it's just a text file containing ips that can be modified ( for adding/removing ips ) at any time, without even having to restart exim in order to apply the new ip pool.