EFS

EFS is a "POP3 Connector" (also known as "mail forwarding" or "mail relay" software etc). It was originally designed to provide a cost-effective way of retrieving Internet based mail and delivering any messages to an internal mail server, such as Microsoft Exchange Server, Lotus Notes/Domino (or in fact any RFC compliant SMTP mail server).

You do not need a fulltime connection to the Internet to run EFS - it works with both static (full time) and dynamic (part time) IP addresses.