I've been thinking about the uid attribute a little bit, and it seems
completely redundant. If pop3d was modified to lookup mail=uid@domain,
we wouldn't have the uniqueness problem, and wouldn't have to invent
stupid uid value schemes like user-domain for the uid attribute value.
The @domain part could be determined by the IP range that the client
is in, or by simply running a different pop3d server per every virtual
domain. Just like Apache does it for virtual domains.
So the pop3 client submits uid to the pop3 server, pop3 server looks at
the ip address of the client. If an address matches a range of particular
virtual server in pop3d's configuration file (this could be a cdb database),
then an ldap search is done with uid@domain that's read from the config
file. The configuration file is simply bunch of range=domain keys and
values.
