I found instructions here showing how to set up a "catchall" address on a Kolab 3.2 install which also worked on my 3.4 install, except that ALL emails went to the catch-all, including emails for existing, genuine users - their mailboxes were not receiving their mail, the catchall was.
I fiddled about with the query_filter in the config file to stop this behaviour. It is still not perfect, as it stops the "user+extrabit@domain.com" addresses from working unless "user+extrabit@domain.com" is setup up as an alias for the user. Perhaps someone cleverer than me can suggest a better query_filter. Anyway, here's the .cf file I used:
# cat virtual_alias_maps_catchall.cf
server_host = localhost
server_port = 389
version = 3
search_base = dc=blogger,dc=co,dc=uk
scope = sub
domain = ldap:/etc/postfix/ldap/mydestination.cf
bind_dn = uid=kolab-service,ou=Special Users,dc=blogger,dc=co,dc=uk
bind_pw = support
query_filter = (&(alias=catchall@%d)(!(alias=%s@%d)))
result_attribute = mail
Follow the rest of the instructions in the link I mentioned before.
This put me on the right track too.
