[exim] mx selection (possibly off topic)

Hi,

     I'm having a problem with an email address that mail is being sent to... 
mx entry below.  Bind9 seems to return the addresses in random order and exim 
intermittently trys to send the email to the 99 weighted server 
'mail-relay.it-tallaght.ie.' which is not configured to accept the mail (the 
other 2 are).  

Has anyone come accross this type of behaviour, can I force exim to try the
lowest weiged server first, or is this a bind thing....

Thanks
           Ruairi

$ nslookup
> set type=mx
> councilofdirectors.ie

Server:         192.168.1.5
Address:        192.168.1.5#53

Non-authoritative answer:
councilofdirectors.ie mail exchanger = 10 193.1.207.2.
councilofdirectors.ie mail exchanger = 20 ns.itnet.ie.
councilofdirectors.ie mail exchanger = 99 mail-relay.it-tallaght.ie.