ImapProxy

apt-get install imapproxy
mcedit /etc/imapproxy.conf

v nastavení

server_hostname localhost
listen_port 1143 #or any other free port, remember I have courier bound to 143 already
listen_address 127.0.0.1
server_port 143
enable_select_cache yes

/etc/init.d/imapproxy restart

Oficiální stránka: http://www.imapproxy.org/