[exim] using name of host in spamd_address

Hello!

I'd like to use hostname instead numeric ip in spamd_address variable.
I've added host to /etc/hosts file:
$ grep sa /etc/hosts
127.0.0.1       sa
$ ping sa
PING sa (127.0.0.1) 56(84) bytes of data.
64 bytes from meteor.mejor.pl (127.0.0.1): icmp_req=1 ttl=60 time=0.000 ms
64 bytes from meteor.mejor.pl (127.0.0.1): icmp_req=2 ttl=60 time=0.000 ms
^C

In exim.conf, in main section i've got:
spamd_address = sa 783
With such configuration exim-4,77 throws to log:
2012-04-04 16:20:59 1SFR4t-0003rv-M8 spam acl condition: warning - spamd
connection to sa, port 783 failed: Network is unreachable

I didn't have such problem with configuring connection to sql server,
hostname works.
Is it possible to use hostname in spamd_address or i'm doing it in wrong
way?

Thanks,
Marcin