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diff --git a/doc/rfc/rfc1725.txt b/doc/rfc/rfc1725.txt new file mode 100644 index 0000000..43fcc51 --- /dev/null +++ b/doc/rfc/rfc1725.txt @@ -0,0 +1,1011 @@ + + + + + + +Network Working Group J. Myers +Request for Comments: 1725 Carnegie Mellon +Obsoletes: 1460 M. Rose +Category: Standards Track Dover Beach Consulting, Inc. + November 1994 + + + Post Office Protocol - Version 3 + +Status of this Memo + + This document specifies an Internet standards track protocol for the + Internet community, and requests discussion and suggestions for + improvements. Please refer to the current edition of the "Internet + Official Protocol Standards" (STD 1) for the standardization state + and status of this protocol. Distribution of this memo is unlimited. + +Overview + + This memo is a revision to RFC 1460, a Draft Standard. It makes the + following changes from that document: + + - removed text regarding "split-UA model", which didn't add + anything to the understanding of POP + + - clarified syntax of commands, keywords, and arguments + + - clarified behavior on broken connection + + - explicitly permitted an inactivity autologout timer + + - clarified the requirements of the "exclusive-access lock" + + - removed implementation-specific wording regarding the parsing of + the maildrop + + - allowed servers to close the connection after a failed + authentication command + + - removed the LAST command + + - fixed typo in example of TOP command + + - clarified that the second argument to the TOP command is non- + negative + + - added the optional UIDL command + + + + +Myers & Rose [Page 1] + +RFC 1725 POP3 November 1994 + + + - added warning regarding length of shared secrets with APOP + + - added additional warnings to the security considerations section + +1. 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. + +2. A Short Digression + + This memo does not specify how a client host enters mail into the + transport system, although a method consistent with the philosophy of + this memo is presented here: + + When the user agent on a client host wishes to enter a message + into the transport system, it establishes an SMTP connection to + its relay host (this relay host could be, but need not be, the + POP3 server host for the client host). + +3. Basic Operation + + Initially, the server host starts the POP3 service by listening on + TCP port 110. When a client host wishes to make use of the service, + it establishes a TCP connection with the server host. When the + connection is established, the POP3 server sends a greeting. The + client and POP3 server then exchange commands and responses + + + +Myers & Rose [Page 2] + +RFC 1725 POP3 November 1994 + + + (respectively) until the connection is closed or aborted. + + Commands in the POP3 consist of a keyword, possibly followed by one + or more arguments. All commands are terminated by a CRLF pair. + Keywords and arguments consist of printable ASCII characters. + Keywords and arguments are each separated by a single SPACE + character. Keywords are three or four characters long. Each argument + may be up to 40 characters long. + + Responses in the POP3 consist of a status indicator and a keyword + possibly followed by additional information. All responses are + terminated by a CRLF pair. There are currently two status + indicators: positive ("+OK") and negative ("-ERR"). + + Responses to certain commands are multi-line. In these cases, which + are clearly indicated below, after sending the first line of the + response and a CRLF, any additional lines are sent, each terminated + by a CRLF pair. When all lines of the response have been sent, a + final line is sent, consisting of a termination octet (decimal code + 046, ".") and a CRLF pair. If any line of the multi-line response + begins with the termination octet, the line is "byte-stuffed" by + pre-pending the termination octet to that line of the response. + Hence a multi-line response is terminated with the five octets + "CRLF.CRLF". When examining a multi-line response, the client checks + to see if the line begins with the termination octet. If so and if + octets other than CRLF follow, the the first octet of the line (the + termination octet) is stripped away. If so and if CRLF immediately + follows the termination character, then the response from the POP + server is ended and the line containing ".CRLF" is not considered + part of the multi-line response. + + A POP3 session progresses through a number of states during its + lifetime. Once the TCP connection has been opened and the POP3 + server has sent the greeting, the session enters the AUTHORIZATION + state. In this state, the client must identify itself to the POP3 + server. Once the client has successfully done this, the server + acquires resources associated with the client's maildrop, and the + session enters the TRANSACTION state. In this state, the client + requests actions on the part of the POP3 server. When the client has + issued the QUIT command, the session enters the UPDATE state. In + this state, the POP3 server releases any resources acquired during + the TRANSACTION state and says goodbye. The TCP connection is then + closed. + + A POP3 server MAY have an inactivity autologout timer. Such a timer + MUST be of at least 10 minutes' duration. The receipt of any command + from the client during that interval should suffice to reset the + autologout timer. When the timer expires, the session does NOT enter + + + +Myers & Rose [Page 3] + +RFC 1725 POP3 November 1994 + + + the UPDATE state--the server should close the TCP connection without + removing any messages or sending any response to the client. + +4. The AUTHORIZATION State + + Once the TCP connection has been opened by a POP3 client, the POP3 + server issues a one line greeting. This can be any string terminated + by CRLF. An example might be: + + S: +OK POP3 server ready + + Note that this greeting is a POP3 reply. The POP3 server should + always give a positive response as the greeting. + + The POP3 session is now in the AUTHORIZATION state. The client must + now identify and authenticate itself to the POP3 server. Two + possible mechanisms for doing this are described in this document, + the USER and PASS command combination and the APOP command. The APOP + command is described later in this document. + + To authenticate using the USER and PASS command combination, the + client must first issue the USER command. If the POP3 server + responds with a positive status indicator ("+OK"), then the client + may issue either the PASS command to complete the authentication, or + the QUIT command to terminate the POP3 session. If the POP3 server + responds with a negative status indicator ("-ERR") to the USER + command, then the client may either issue a new authentication + command or may issue the QUIT command. + + When the client issues the PASS command, the POP3 server uses the + argument pair from the USER and PASS commands to determine if the + client should be given access to the appropriate maildrop. + + Once the POP3 server has determined through the use of any + authentication command that the client should be given access to the + appropriate maildrop, the POP3 server then acquires an exclusive- + access lock on the maildrop, as necessary to prevent messages from + being modified or removed before the session enters the UPDATE state. + If the lock is successfully acquired, the POP3 server responds with a + positive status indicator. The POP3 session now enters the + TRANSACTION state, with no messages marked as deleted. If the the + maildrop cannot be opened for some reason (for example, a lock can + not be acquired, the client is denied access to the appropriate + maildrop, or the maildrop cannot be parsed), the POP3 server responds + with a negative status indicator. (If a lock was acquired but the + POP3 server intends to respond with a negative status indicator, the + POP3 server must release the lock prior to rejecting the command.) + After returning a negative status indicator, the server may close the + + + +Myers & Rose [Page 4] + +RFC 1725 POP3 November 1994 + + + connection. If the server does not close the connection, the client + may either issue a new authentication command and start again, or the + client may issue the QUIT command. + + After the POP3 server has opened the maildrop, it assigns a message- + number to each message, and notes the size of each message in octets. + The first message in the maildrop is assigned a message-number of + "1", the second is assigned "2", and so on, so that the n'th message + in a maildrop is assigned a message-number of "n". In POP3 commands + and responses, all message-number's and message sizes are expressed + in base-10 (i.e., decimal). + + Here are summaries for the three POP3 commands discussed thus far: + + USER name + + Arguments: + a string identifying a mailbox (required), which is of + significance ONLY to the server + + Restrictions: + may only be given in the AUTHORIZATION state after the POP3 + greeting or after an unsuccessful USER or PASS command + + Possible Responses: + +OK name is a valid mailbox + -ERR never heard of mailbox name + + Examples: + C: USER mrose + S: +OK mrose is a real hoopy frood + ... + C: USER frated + S: -ERR sorry, no mailbox for frated here + + PASS string + + Arguments: + a server/mailbox-specific password (required) + + Restrictions: + may only be given in the AUTHORIZATION state after a + successful USER command + + Discussion: + Since the PASS command has exactly one argument, a POP3 + server may treat spaces in the argument as part of the + password, instead of as argument separators. + + + +Myers & Rose [Page 5] + +RFC 1725 POP3 November 1994 + + + Possible Responses: + +OK maildrop locked and ready + -ERR invalid password + -ERR unable to lock maildrop + + Examples: + C: USER mrose + S: +OK mrose is a real hoopy frood + C: PASS secret + S: +OK mrose's maildrop has 2 messages (320 octets) + ... + C: USER mrose + S: +OK mrose is a real hoopy frood + C: PASS secret + S: -ERR maildrop already locked + + QUIT + + Arguments: none + + Restrictions: none + + Possible Responses: + +OK + + Examples: + C: QUIT + S: +OK dewey POP3 server signing off + +5. The TRANSACTION State + + Once the client has successfully identified itself to the POP3 server + and the POP3 server has locked and opened the appropriate maildrop, + the POP3 session is now in the TRANSACTION state. The client may now + issue any of the following POP3 commands repeatedly. After each + command, the POP3 server issues a response. Eventually, the client + issues the QUIT command and the POP3 session enters the UPDATE state. + + Here are the POP3 commands valid in the TRANSACTION state: + + STAT + + Arguments: none + + Restrictions: + may only be given in the TRANSACTION state + + + + + +Myers & Rose [Page 6] + +RFC 1725 POP3 November 1994 + + + Discussion: + The POP3 server issues a positive response with a line + containing information for the maildrop. This line is + called a "drop listing" for that maildrop. + + In order to simplify parsing, all POP3 servers required to + use a certain format for drop listings. The positive + response consists of "+OK" followed by a single space, the + number of messages in the maildrop, a single space, and the + size of the maildrop in octets. This memo makes no + requirement on what follows the maildrop size. Minimal + implementations should just end that line of the response + with a CRLF pair. More advanced implementations may + include other information. + + NOTE: This memo STRONGLY discourages implementations + from supplying additional information in the drop + listing. Other, optional, facilities are discussed + later on which permit the client to parse the messages + in the maildrop. + + Note that messages marked as deleted are not counted in + either total. + + Possible Responses: + +OK nn mm + + Examples: + C: STAT + S: +OK 2 320 + + LIST [msg] + + Arguments: + a message-number (optional), which, if present, may NOT + refer to a message marked as deleted + + Restrictions: + may only be given in the TRANSACTION state + + Discussion: + If an argument was given and the POP3 server issues a + positive response with a line containing information for + that message. This line is called a "scan listing" for + that message. + + If no argument was given and the POP3 server issues a + positive response, then the response given is multi-line. + + + +Myers & Rose [Page 7] + +RFC 1725 POP3 November 1994 + + + After the initial +OK, for each message in the maildrop, + the POP3 server responds with a line containing information + for that message. This line is also called a "scan + listing" for that message. + + In order to simplify parsing, all POP3 servers are required + to use a certain format for scan listings. A scan listing + consists of the message-number of the message, followed by + a single space and the exact size of the message in octets. + This memo makes no requirement on what follows the message + size in the scan listing. Minimal implementations should + just end that line of the response with a CRLF pair. More + advanced implementations may include other information, as + parsed from the message. + + NOTE: This memo STRONGLY discourages implementations + from supplying additional information in the scan + listing. Other, optional, facilities are discussed + later on which permit the client to parse the messages + in the maildrop. + + Note that messages marked as deleted are not listed. + + Possible Responses: + +OK scan listing follows + -ERR no such message + + Examples: + C: LIST + S: +OK 2 messages (320 octets) + S: 1 120 + S: 2 200 + S: . + ... + C: LIST 2 + S: +OK 2 200 + ... + C: LIST 3 + S: -ERR no such message, only 2 messages in maildrop + + RETR msg + + Arguments: + a message-number (required) which may not refer to a + message marked as deleted + + Restrictions: + may only be given in the TRANSACTION state + + + +Myers & Rose [Page 8] + +RFC 1725 POP3 November 1994 + + + Discussion: + If the POP3 server issues a positive response, then the + response given is multi-line. After the initial +OK, the + POP3 server sends the message corresponding to the given + message-number, being careful to byte-stuff the termination + character (as with all multi-line responses). + + Possible Responses: + +OK message follows + -ERR no such message + + Examples: + C: RETR 1 + S: +OK 120 octets + S: <the POP3 server sends the entire message here> + S: . + + DELE msg + + Arguments: + a message-number (required) which may not refer to a + message marked as deleted + + Restrictions: + may only be given in the TRANSACTION state + + Discussion: + The POP3 server marks the message as deleted. Any future + reference to the message-number associated with the message + in a POP3 command generates an error. The POP3 server does + not actually delete the message until the POP3 session + enters the UPDATE state. + + Possible Responses: + +OK message deleted + -ERR no such message + + Examples: + C: DELE 1 + S: +OK message 1 deleted + ... + C: DELE 2 + S: -ERR message 2 already deleted + + NOOP + + Arguments: none + + + + +Myers & Rose [Page 9] + +RFC 1725 POP3 November 1994 + + + Restrictions: + may only be given in the TRANSACTION state + + Discussion: + The POP3 server does nothing, it merely replies with a + positive response. + + Possible Responses: + +OK + + Examples: + C: NOOP + S: +OK + + RSET + + Arguments: none + + Restrictions: + may only be given in the TRANSACTION state + + Discussion: + If any messages have been marked as deleted by the POP3 + server, they are unmarked. The POP3 server then replies + with a positive response. + + Possible Responses: + +OK + + Examples: + C: RSET + S: +OK maildrop has 2 messages (320 octets) + +6. The UPDATE State + + When the client issues the QUIT command from the TRANSACTION state, + the POP3 session enters the UPDATE state. (Note that if the client + issues the QUIT command from the AUTHORIZATION state, the POP3 + session terminates but does NOT enter the UPDATE state.) + + If a session terminates for some reason other than a client-issued + QUIT command, the POP3 session does NOT enter the UPDATE state and + MUST not remove any messages from the maildrop. + + QUIT + + Arguments: none + + + + +Myers & Rose [Page 10] + +RFC 1725 POP3 November 1994 + + + Restrictions: none + + Discussion: + The POP3 server removes all messages marked as deleted from + the maildrop. It then releases any exclusive-access lock + on the maildrop and replies as to the status of these + operations. The TCP connection is then closed. + + Possible Responses: + +OK + + Examples: + C: QUIT + S: +OK dewey POP3 server signing off (maildrop empty) + ... + C: QUIT + S: +OK dewey POP3 server signing off (2 messages left) + ... + +7. Optional POP3 Commands + + The POP3 commands discussed above must be supported by all minimal + implementations of POP3 servers. + + The optional POP3 commands described below permit a POP3 client + greater freedom in message handling, while preserving a simple POP3 + server implementation. + + NOTE: This memo STRONGLY encourages implementations to support + these commands in lieu of developing augmented drop and scan + listings. In short, the philosophy of this memo is to put + intelligence in the part of the POP3 client and not the POP3 + server. + + TOP msg n + + Arguments: + a message-number (required) which may NOT refer to to a + message marked as deleted, and a non-negative number + (required) + + Restrictions: + may only be given in the TRANSACTION state + + Discussion: + If the POP3 server issues a positive response, then the + response given is multi-line. After the initial +OK, the + POP3 server sends the headers of the message, the blank + + + +Myers & Rose [Page 11] + +RFC 1725 POP3 November 1994 + + + line separating the headers from the body, and then the + number of lines indicated message's body, being careful to + byte-stuff the termination character (as with all multi- + line responses). + + Note that if the number of lines requested by the POP3 + client is greater than than the number of lines in the + body, then the POP3 server sends the entire message. + + Possible Responses: + +OK top of message follows + -ERR no such message + + Examples: + C: TOP 1 10 + S: +OK + S: <the POP3 server sends the headers of the + message, a blank line, and the first 10 lines + of the body of the message> + S: . + ... + C: TOP 100 3 + S: -ERR no such message + + UIDL [msg] + + Arguments: + a message-number (optionally) If a message-number is given, + it may NOT refer to a message marked as deleted. + + Restrictions: + may only be given in the TRANSACTION state. + + Discussion: + If an argument was given and the POP3 server issues a positive + response with a line containing information for that message. + This line is called a "unique-id listing" for that message. + + If no argument was given and the POP3 server issues a positive + response, then the response given is multi-line. After the + initial +OK, for each message in the maildrop, the POP3 server + responds with a line containing information for that message. + This line is called a "unique-id listing" for that message. + + In order to simplify parsing, all POP3 servers are required to + use a certain format for unique-id listings. A unique-id + listing consists of the message-number of the message, + followed by a single space and the unique-id of the message. + + + +Myers & Rose [Page 12] + +RFC 1725 POP3 November 1994 + + + No information follows the unique-id in the unique-id listing. + + The unique-id of a message is an arbitrary server-determined + string, consisting of characters in the range 0x21 to 0x7E, + which uniquely identifies a message within a maildrop and + which persists across sessions. The server should never reuse + an unique-id in a given maildrop, for as long as the entity + using the unique-id exists. + + Note that messages marked as deleted are not listed. + + Possible Responses: + +OK unique-id listing follows + -ERR no such message + + Examples: + C: UIDL + S: +OK + S: 1 whqtswO00WBw418f9t5JxYwZ + S: 2 QhdPYR:00WBw1Ph7x7 + S: . + ... + C: UIDL 2 + S: +OK 2 QhdPYR:00WBw1Ph7x7 + ... + C: UIDL 3 + S: -ERR no such message, only 2 messages in maildrop + + APOP name digest + + Arguments: + a string identifying a mailbox and a MD5 digest string + (both required) + + Restrictions: + may only be given in the AUTHORIZATION state after the POP3 + greeting + + Discussion: + Normally, each POP3 session starts with a USER/PASS + exchange. This results in a server/user-id specific + password being sent in the clear on the network. For + intermittent use of POP3, this may not introduce a sizable + risk. However, many POP3 client implementations connect to + the POP3 server on a regular basis -- to check for new + mail. Further the interval of session initiation may be on + the order of five minutes. Hence, the risk of password + capture is greatly enhanced. + + + +Myers & Rose [Page 13] + +RFC 1725 POP3 November 1994 + + + An alternate method of authentication is required which + provides for both origin authentication and replay + protection, but which does not involve sending a password + in the clear over the network. The APOP command provides + this functionality. + + A POP3 server which implements the APOP command will + include a timestamp in its banner greeting. The syntax of + the timestamp corresponds to the `msg-id' in [RFC822], and + MUST be different each time the POP3 server issues a banner + greeting. For example, on a UNIX implementation in which a + separate UNIX process is used for each instance of a POP3 + server, the syntax of the timestamp might be: + + <process-ID.clock@hostname> + + where `process-ID' is the decimal value of the process's + PID, clock is the decimal value of the system clock, and + hostname is the fully-qualified domain-name corresponding + to the host where the POP3 server is running. + + The POP3 client makes note of this timestamp, and then + issues the APOP command. The `name' parameter has + identical semantics to the `name' parameter of the USER + command. The `digest' parameter is calculated by applying + the MD5 algorithm [RFC1321] to a string consisting of the + timestamp (including angle-brackets) followed by a shared + secret. This shared secret is a string known only to the + POP3 client and server. Great care should be taken to + prevent unauthorized disclosure of the secret, as knowledge + of the secret will allow any entity to successfully + masquerade as the named user. The `digest' parameter + itself is a 16-octet value which is sent in hexadecimal + format, using lower-case ASCII characters. + + When the POP3 server receives the APOP command, it verifies + the digest provided. If the digest is correct, the POP3 + server issues a positive response, and the POP3 session + enters the TRANSACTION state. Otherwise, a negative + response is issued and the POP3 session remains in the + AUTHORIZATION state. + + Note that as the length of the shared secret increases, so + does the difficulty of deriving it. As such, shared + secrets should be long strings (considerably longer than + the 8-character example shown below). + + + + + +Myers & Rose [Page 14] + +RFC 1725 POP3 November 1994 + + + Possible Responses: + +OK maildrop locked and ready + -ERR permission denied + + Examples: + S: +OK POP3 server ready <1896.697170952@dbc.mtview.ca.us> + C: APOP mrose c4c9334bac560ecc979e58001b3e22fb + S: +OK maildrop has 1 message (369 octets) + + In this example, the shared secret is the string `tan- + staaf'. Hence, the MD5 algorithm is applied to the string + + <1896.697170952@dbc.mtview.ca.us>tanstaaf + + which produces a digest value of + + c4c9334bac560ecc979e58001b3e22fb + +8. POP3 Command Summary + + Minimal POP3 Commands: + + USER name valid in the AUTHORIZATION state + PASS string + QUIT + + STAT valid in the TRANSACTION state + LIST [msg] + RETR msg + DELE msg + NOOP + RSET + + QUIT valid in the UPDATE state + + Optional POP3 Commands: + + APOP name digest valid in the AUTHORIZATION state + + TOP msg n valid in the TRANSACTION state + UIDL [msg] + + POP3 Replies: + + +OK + -ERR + + + + + +Myers & Rose [Page 15] + +RFC 1725 POP3 November 1994 + + + Note that with the exception of the STAT, LIST, and UIDL commands, + the reply given by the POP3 server to any command is significant only + to "+OK" and "-ERR". Any text occurring after this reply may be + ignored by the client. + +9. Example POP3 Session + + S: <wait for connection on TCP port 110> + C: <open connection> + S: +OK POP3 server ready <1896.697170952@dbc.mtview.ca.us> + C: APOP mrose c4c9334bac560ecc979e58001b3e22fb + S: +OK mrose's maildrop has 2 messages (320 octets) + C: STAT + S: +OK 2 320 + C: LIST + S: +OK 2 messages (320 octets) + S: 1 120 + S: 2 200 + S: . + C: RETR 1 + S: +OK 120 octets + S: <the POP3 server sends message 1> + S: . + C: DELE 1 + S: +OK message 1 deleted + C: RETR 2 + S: +OK 200 octets + S: <the POP3 server sends message 2> + S: . + C: DELE 2 + S: +OK message 2 deleted + C: QUIT + S: +OK dewey POP3 server signing off (maildrop empty) + C: <close connection> + S: <wait for next connection> + +10. Message Format + + All messages transmitted during a POP3 session are assumed to conform + to the standard for the format of Internet text messages [RFC822]. + + It is important to note that the octet count for a message on the + server host may differ from the octet count assigned to that message + due to local conventions for designating end-of-line. Usually, + during the AUTHORIZATION state of the POP3 session, the POP3 server + can calculate the size of each message in octets when it opens the + maildrop. For example, if the POP3 server host internally represents + end-of-line as a single character, then the POP3 server simply counts + + + +Myers & Rose [Page 16] + +RFC 1725 POP3 November 1994 + + + each occurrence of this character in a message as two octets. Note + that lines in the message which start with the termination octet need + not be counted twice, since the POP3 client will remove all byte- + stuffed termination characters when it receives a multi-line + response. + +11. References + + [RFC821] Postel, J., "Simple Mail Transfer Protocol", STD 10, RFC + 821, USC/Information Sciences Institute, August 1982. + + [RFC822] Crocker, D., "Standard for the Format of ARPA-Internet Text + Messages", STD 11, RFC 822, University of Delaware, August 1982. + + [RFC1321] Rivest, R. "The MD5 Message-Digest Algorithm", RFC 1321, + MIT Laboratory for Computer Science, April, 1992. + +12. Security Considerations + + It is conjectured that use of the APOP command provides origin + identification and replay protection for a POP3 session. + Accordingly, a POP3 server which implements both the PASS and APOP + commands must not allow both methods of access for a given user; that + is, for a given "USER name" either the PASS or APOP command is + allowed, but not both. + + Further, note that as the length of the shared secret increases, so + does the difficulty of deriving it. + + Servers that answer -ERR to the USER command are giving potential + attackers clues about which names are valid + + Use of the PASS command sends passwords in the clear over the + network. + + Use of the RETR and TOP commands sends mail in the clear over the + network. + + Otherwise, security issues are not discussed in this memo. + +13. Acknowledgements + + The POP family has a long and checkered history. Although primarily + a minor revision to RFC 1460, POP3 is based on the ideas presented in + RFCs 918, 937, and 1081. + + In addition, Alfred Grimstad, Keith McCloghrie, and Neil Ostroff + provided significant comments on the APOP command. + + + +Myers & Rose [Page 17] + +RFC 1725 POP3 November 1994 + + +14. Authors' Addresses + + John G. Myers + Carnegie-Mellon University + 5000 Forbes Ave + Pittsburgh, PA 15213 + + EMail: jgm+@cmu.edu + + + Marshall T. Rose + Dover Beach Consulting, Inc. + 420 Whisman Court + Mountain View, CA 94043-2186 + + EMail: mrose@dbc.mtview.ca.us + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +Myers & Rose [Page 18] + |