Remote Mail Checking Protocol (RFC1339)
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2019-Feb-11
Internet Society Requests For Comment (RFCs)
S. Dorner: AUTHOR [+1]
This RFC defines a protocol to provide a mail checking service to be used between a client and server pair. Typically, a small program on a client workstation would use the protocol to query a server in order to find out whether new mail has arrived for a specified user. This memo defines an Experimental Protocol for the Internet community.
Network Working Group S. Dorner Request for Comments: 1339 P. Resnick U. of Illinois at Urbana-Champaign June 1992
Remote Mail Checking Protocol
Status of this Memo
This memo defines an Experimental Protocol for the Internet community. Discussion and suggestions for improvement are requested. Please refer to the current edition of the "IAB Official Protocol Standards" for the standardization state and status of this protocol. Distribution of this memo is unlimited.
This RFC defines a protocol to provide a mail checking service to be used between a client and server pair. Typically, a small program on a client workstation would use the protocol to query a server in order to find out whether new mail has arrived for a specified user.
This RFC defines a simple, low-overhead protocol for checking the status of a maildrop on a host. It is primarily intended for use in adjunct with "remote mail" servers such as those implementing the Post Office Protocol (RFC 1225). Remote mail clients must poll their servers to discover the arrival of mail. Using one of the remote mail protocols for periodic checking can be quite impractical and expensive for the server since either a constant connection between client and server must be maintained or repeated and expensive user validations must be done. Furthermore, users on less capable computers may not wish to devote the memory required to have a full implementation of the client polling for mail. Thus, we feel that an easy to implement and inexpensive to use polling scheme would be of benefit both to mail servers and their clients.
To avoid connection overhead, the Remote Mail Checking Protocol is based on the User Datagram Protocol (UDP), using UDP port 50 decimal (62 octal) for the server. The protocol provides for both non- authenticated and authenticated polling. Non-authenticated polling is simplest for both client and server. Authenticated polling provides a small increment of privacy, at the cost of more complexity in both client and server (but still far less than polling with one of the
Dorner & Resnick [Page 1]
RFC 1339 Remote Mail Checking Protocol June 1992
remote mail protocols).
In the non-authenticated version of the protocol, the server will listen on port 50 for maildrop check requests for users with maildrops on the machine. A client will send a single UDP datagram from a randomly chosen unreserved UDP port to UDP port 50 on the server. The datagram will contain a 32-bit (four-octet) number which is set to all zeros (0), followed by a case-sensitive ASCII string of a username on the server system. The server will find the maildrop on the system for that user and determine the amount of time that has passed since the last message in the maildrop was appended, as well as the amount of time that has passed since the maildrop was last accessed for reading. The server will then send back a single UDP datagram containing three 32-bit num...