[Exim] LDAP: both mailbox and alias delivery at the same tim…

Hi,
at the moment I am trying to set up an Exim server which should replace
a Netscape Messaging Server. Therefore I am doing LDAP queries for
all delivery options.

But Netscape allows simultaneous use of "maildeliveryoption: mailbox"
and "mailforwardingaddress: mail@address", which means that each mail
is stored in the user's mailbox AND forwarded to another address.

At the moment I am using the following director for the forward
delivery (ou and o attributes changed):

ldap_alias2:
  driver = aliasfile
  search_type = ldap
  queries = ldap::///ou=xyz,o=abc\
                     ?MailForwardingAddress?sub?(|(mail=$local_part@$domain)\
                     (MailAlternateAddress=$local_part@$domain)\
                     (MailAlternateAddress=@$domain))
  file_transport = address_file
  pipe_transport = address_pipe 

I tried to expand it for simultaneous forwarding and storing:

ldap_alias1:
  driver = aliasfile
  search_type = ldap
  queries = ldap::///ou=xyz,o=abc\
                     ?MailForwardingAddress,uid?sub?(&(|(mail=$local_part@$domain)\
                     (MailAlternateAddress=$local_part@$domain)\
                     (MailAlternateAddress=@$domain))(maildeliveryoption=mailbox))
  file_transport = address_file
  pipe_transport = address_pipe

But this returns full LDIF lines instead of only the field's contents,
so that exim cannot make any use of it.

Now I am in need of assistance and would be very thankful if someone
has an idea how to handle this correctly.

Thanks in advance,
Marc