"Introduction On certain types of smaller nodes in the Internet it is often impractical to maintain a message transport system (MTS). For example@ a workstation may not have sufficient resources (cycles@ disk space) in order to permit a SMTP server [RFC821] and associated local mail delivery system to be kept resident and continuously running. Similarly@ it may be expensive (or impossible) to keep a personal computer interconnected to an IP-style network for long amounts of time (the node is lacking the resource known as ""connectivity""). Despite this@ it is often very useful to be able to manage mail on these smaller nodes@ and they often support a user agent (UA) to aid the tasks of mail handling. To solve this problem@ a node which can support an MTS entity offers a maildrop service to these less endowed nodes. The Post Office Protocol - Version 3 (POP3) is intended to permit a workstation to dynamically access a maildrop on a server host in a useful fashion. Usually@ this means that the POP3 is used to allow a workstation to retrieve mail that the server is holding for it. For the remainder of this memo@ the term ""client host"" refers to a host making use of the POP3 service@ while the term ""server host"" refers to a host which offers the POP3 service."