RFC 1064 (rfc1064) - Page 1 of 26
Interactive Mail Access Protocol: Version 2
Alternative Format: Original Text Document
Network Working Group M. Crispin
Request for Comments: 1064 SUMEX-AIM
July 1988
INTERACTIVE MAIL ACCESS PROTOCOL - VERSION 2
Status of this Memo
This RFC suggests a method for workstations to dynamically access
mail from a mailbox server ("repository"). This RFC specifies a
standard for the SUMEX-AIM community and a proposed experimental
protocol for the Internet community. Discussion and suggestions for
improvement are requested. Distribution of this memo is unlimited.
Introduction
The intent of the Interactive Mail Access Protocol, Version 2 (IMAP2)
is to allow a workstation or similar small machine to access
electronic mail from a mailbox server. IMAP2 is the protocol used by
the SUMEX-AIM MM-D (MM Distributed) mail system.
Although different in many ways from POP2 (RFC 937), IMAP2 may be
thought of as a functional superset of POP2, and the POP2 RFC was
used as a model for this RFC. There was a cognizant reason for this;
RFC 937 deals with an identical problem and it was desirable to offer
a basis for comparison.
Like POP2, IMAP2 specifies a means of accessing stored mail and not
of posting mail; this function is handled by a mail transfer protocol
such as SMTP (RFC 821). A comparison with the DMSP protocol of
PCMAIL can be found at the end of "System Model and Philosophy"
section.
This protocol assumes a reliable data stream such as provided by TCP
or any similar protocol. When TCP is used, the IMAP2 server listens
on port 143.
System Model and Philosophy
Electronic mail is a primary means of communication for the widely
spread SUMEX-AIM community. The advent of distributed workstations
is forcing a significant rethinking of the mechanisms employed to
manage such mail. With mainframes, each user tends to receive and
process mail at the computer he used most of the time, his "primary
host". The first inclination of many users when an independent
workstation is placed in front of them is to begin receiving mail at
the workstation, and, in fact, many vendors have implemented
Crispin