[Exim4U] Multi IP setup : are new network interfaces required ?

Hello, I have been running exim4u with a single domain for a few months. Now I am activating the multi IP setup before migrating my 3 domains from Vexim to Exim4u, here are my questions : Do I need to configure new network interface for each additionnal IP on my host ? If so, what are the servers (horde ? imap ? exim ?) that must or may take advantage of the additionnal IP by listening on a new interface associated to the IP ? -- Thomas