Smunge is a stand alone POP3 funneling proxy server, designed 
to allow clients to attach to multiple pop servers as if they 
were one. Smunge can be used to join together multiple mailboxes, 
or to present different users with different mailboxes (depending 
on username). This allows for administrators of pop servers to set 
up either load balancing or redundant clusters for pop services. 
It was initially designed to smooth over the transition of pop 
services from one machine to another, without users losing mail 
(by keeping the old server active whilst the new one was being 
installed). It also supports DRAC for pop-before-smtp authentication. 
Also featured is support for LDAP based authentication and lookups 
for mapping users to sets of pop servers.

WWW: http://www.i2pi.com/smunge/