[Exim] using only the left column of a file in a domain list

Hi everybody,

on my machine (which runs exim4), I have a file containung two columns

# domain name     additional data
domain1.com        data1
domain2.com        data2

I'd like to tell exim: Add any domain which appears in the left column
of this file to your list of local domains.

Any idea how to do this?

Martin