stopping exim4 from hanging on startup with no network

[Micha Feigin <michf@post.tau.ac.il>]

I have exim4 setup on a laptop, thus the network isn't always available
when the system starts up.
The problem is that when the network isn't found it hangs for about a
minute before it gives up and lets the boot process continue which is
very annoying. I think it is hanging on trying to connect to the
smarthost but I'm not sure.
Any way to tell it to do that in the background, avoid the check on
startup or give up faster?

Thanx