pop3 caching proxy [closed]
Solution 1:
I would use fetchmail to download the mail to a server every few minutes then use dovecot to serve it up as POP3 or IMAP
Both are relatively easy to configure.
Solution 2:
You could use fetchmail to get the mails from the remote server. All users can then use the ubuntu server as their mail server and pull the mails locally.
The needed effort on the server side is relatively low, but you need to configure the local pop3 server on all clients.