[Exim] reverse DNS lookup for virtual domains

Hi,

I've got a question. I'm just setting up my Exim server (version 3.35 as
shipped with Debian 'testing'). I have a server (flizzle.net) with
several subdomains on the same IP. Exim, however, always does a reverse
DNS lookup, finds the wrong hostname (e.g. when mail arrives for
cantr.net, one of the virtual domains, it looks up the IP, and finds
flizzle.net), and then refuses the mail. How can I make it that the
server does not lookup hostnames that are considered local?

Any help would be appreciated! :)

Jos