[Exim] host_lookup using a serach

I'm running Exim 3.22
I have 100 addresses that are nats from my internal network into the dmz
where exim resides.
I want to stop Exim from doing a host_lookup on these addresses.
This is what I was considering:
host_lookup = !lsearch;/etc/mail/hosts.nolookup

contents of the hosts.nolookup file would be:
10.10.*

Will this work?

Owen C. Creger CCNA, CISSP
Info. Sec. Administrator
Creative Solutions, a Thomson Company.
7322 Newman Blvd.
Dexter, MI 48130
email: ocreger@???
ph: 734-426-5860 ex. 3787
fax: 734-426-5946
cell: 734-223-6270