Efficient Mail Submission and Delivery (EMSD) is a network protocol. The protocol is described in RFC 2524. EMSD is intended for limited use in private wireless IP networks. However, it is unsuitable for general purpose message transfer or for transfer of messages over the Internet due to the following limitations: * Lack of congestion control * Inadequate security due to lack of encryption (clear text passwords) * Lack of character set internationalization * Poorly defined gatewaying to and from Internet Mail Use cases for EMSD * Wireless links with adequate link-layer encryption and gatewayed to the public Internet * A private IP network that is either very over-provisioned or has some means of congestion control