[Exim] LDAP local_domain lookup

I'm attempting to set the

local_domains

variable in my /usr/exim/configure by way of an LDAP lookup.

ie. local_domains =
ldapm;ldap::///ou=visps,o=test.com?vispdomainpattern?sub?(vispstatus=active)

Lets say the standard LDAP query (when run in a brower):-

ldap::///ou=visps,o=test.com?vispdomainpattern?sub?(vispstatus=active)

returns two entries:-

somedomain.com
anotherdomain.com

I am therefore thinking that my mailserver will accept mail for:-

someuser@??? &
someuser@???

However, the server seems to accept mail for ANY domain, almost
as if I had set:-

local_domains = *

Could anyone tell me whats going wrong or point me in the right direction to
help me solve my problem?

tia.

d.