a document delivery network server having a set of integrated functions including sending , receiving , routing and filing of faxes and e - mails to other users which achieves numerous advantages over the prior art . the document delivery system is based on a client / server model having both analog and digital fax line capabilities . the server side provides very highly integrated systems functionality based on industry standard , commercially available hardware and a mix of industry standard and proprietary software components including integrated fax / modem modules , an embedded os , embedded plug - and - play driver sets , embedded e - mail gateways , an embedded fax archive , embedded back - up / restore , proprietary high efficiency line utilization and highly efficient load balancing .