[exim] (no subject)

Hi

would someone know how I can fix, get this working.

[root@ns tmp]# rpm -Uvh exim-4.50-2_12.rhfc1.at.i386.rpm
warning: exim-4.50-2_12.rhfc1.at.i386.rpm: V3 DSA signature: NOKEY, key 
ID 66534c2b
error: Failed dependencies:
         /etc/aliases is needed by exim-4.50-2_12.rhfc1.at

Thanks, if anyone would be so kind to help.

Kind Regards
Brent Clark