RFC 1339 (rfc1339) - Page 2 of 6

Remote Mail Checking Protocol

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:








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