RFC 1339 (rfc1339) - Page 2 of 6
Remote Mail Checking Protocol
Alternative Format: Original Text Document
RFC 1339 Remote Mail Checking Protocol June 1992 remote mail protocols). Non-Authenticated Protocol 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 numbers in network byte order to the originating port on the client. Again, the first will be zero (0), the second will contain the number of seconds plus one since the last addition to the specified user's maildrop and the third will contain the number of seconds plus one since the last read on the user's maildrop. If the username provided does not exist, if the maildrop is not on the system or if the maildrop is empty, the server will send back zero (0) in the last two numbers for its reply. The client will consider the maildrop to contain new mail if the number of seconds since the last read access is greater than or equal to the number of seconds since the last addition access of the maildrop and either number is non-zero, old mail if the number of seconds since the last read access is less than or equal to the number of seconds since the last addition access of the maildrop and either number is non-zero, and empty if both numbers are zero. Authenticated Protocol The authenticated protocol operates identically to the non- authenticated protocol with the exception of the first interaction between the server and the client. After the client has sent its initial request containing the requested username, the server will send back a single UDP packet containing three 32-bit numbers. The first number will be a bit-mask instead of the normal 32-bits of zero. The bit-mask will indicate a request for authentication. Each bit in the mask represents a type of authentication that the server accepts. The bits (with the least significant bit numbered 0, and the most significant bit 31) are defined as follows: Dorner & Resnick
