Subject: LAN Mail Protocols Summary Newsgroups: comp.mail.misc,news.answers,comp.answers From: jmwobus@mailbox.syr.edu (John Wobus) Date: Tue, 29 Mar 1994 21:52:31 GMT Archive-name: LANs/mail-protocols Serving PCs and Workstations Using a Central Mail Server on an Internet ------- --- --- ------------ ----- - ------- ---- ------ -- -- -------- (Note: this message is prepared by John Wobus of Syracuse University, jmwobus@mailbox.syr.edu who welcomes updates and corrections; this memo has not been checked very carefully and requires a lot of correction at this time. The last update was made 3/9/1994). There are advantages to collecting mail destined to PCs and workstations on a central server, to be turned over to the PC or workstation on demand: - Your PC or workstation may be down quite a bit and less network bandwidth and less of the processing resouces of the sending computer are used if the computer receiving your mail is ready. - Some people use more than one PC or workstation to read mail. - A PC or workstation may not have the resources to store all the mail you receive. - It can make your e-mail address more like other users'. The easiest way to "implement" this is to run the central mail server like any multi-user system: let people sign on to it and use some mail utility. Then PC and workstation users can use "terminal sessions" to sign on to the central mail server and read their mail. This has the disadvantage of making the PC and workstation users learn and use the central mail server's procedures. SMTP, the "internet" mail protocol used to deliver mail between multi-user systems only supports mail transfer initiated by the sender (actually, it has a method to initiate reception, but the method didn't catch on and is not used). Other protocols have been devised to allow a workstation or PC to request transfer of mail, thus able to make use of a cnetral server. These include the published protocols POP (probably not used anymore), POP2, POP3, IMAP2, IMAP3 (not used), IMAP4 and DMSP. POP, POP2, POP3: These are rather minimal and are designed to be so. The three are similar but not enough alike to be interoperable. They are basically designed to identify the user by username and password, to transfer the mail from server to PC or workstation and to delete the mail transferred. It is assumed that SMTP will be used to send mail. Messages can be retrieved individually, but the only information you can get about a message without transferring it is its length in bytes-- useful for PCs with limited storage. POP2 and POP3 are still used a good deal. POP3 has a couple of optional extensions: one to avoid sending passwords, and one to aid in reading bulletin boards. IMAP2, IMAP3, IMAP4: The IMAP family is similar to the POP family, but also gives clients a way to do string searches through mail that still resides on the server. This is designed to allow the PC or workstation to be more selective as to which mail will be transferred. The POP protocols, on the other hand, are designed for simpler server software. IMAP2 is used quite a bit. IMAP3 is an incompatible offshoot that has not been implemented much. IMAP4 is a relatively recent extension of IMAP2 which makes the servers cogniscent of the MIME-structure of a message. IMAP4 also extends IMAP to have some of DMSP's features. DMSP (aka PCMAIL): PCs and workstations can use this protocol to both send and receive mail. The system is designed around the idea that each user can own more than one workstation; however, the system doesn't seem to handle the idea of a "public workstation" very well. The PCs and workstations are assumed to hold state information about the mail, a directory so to speak, and when the PC or workstation is connected to the server, this directory is updated to "reality". Issue of Remote Access: Modern commercial e-mail packages typically have features designed to assist in remote access of ones e-mail. Features include: -ability to download mail through a modem -ability to synchronize two different systems which you are using to read your e-mail by plugging them together. Any method of reading e-mail using PCs or Macintoshes can be used remotely via the "PCanywhere(tm)" method, e.g. by dialing up your own office PC and using one of the several kinds of software that allow you to control your PC over the phone. Also, any LAN-based method can be used by using one of the several methods of providing the same protocol support over dialup lines as are on LANs (SLIP or PPP for the above-mentioned, TCP/IP-based protocols, ARA for Appletalk-based protocols, etc, and sometimes using two different protocols, one incapsulated in the other) under the constraint that any operations that use the network will be much slower. Also, POP3 is often used directly over modems (for example, Eudora can be used in this manner). The ideal protocol for remote access would not penalize the user for the much slower communications speed (usually slower by a factor of 100: note that a lot of LAN-based software was written without regard to minimizing the necessary communication, thus is really hurt by such slow speeds), yet would allow the same software to run both remotely and locally, with a wonderful user interface. It would also not be overly expensive in communications equipment or services. This is a difficult set of objectives and the above-three protocols can achieve some of them for some users, but what they actually achieve depends a lot on the user's pattern of e-mail usage. If a user reads just a small amount of mail, then we would not worry about the length of time necessary to download it remotely with POP3, but if the person receives a lot of mail, but just wants to read a small amount of it at home, then with IMAP2, they could pick and choose what to read, eliminating some download time. If someone is paying for the telephone line time (possibly the user if it is a long distance call; in any case, the institution pays a monthly fee for each line it offers, which is dependent upon how many users it is serving, how often they call, and how long their calls are) then IMAP2's natural method of usage which requires the phone call to remain while a user is reading, poking around, sending, and rearranging mail can be much more costly than using POP3 if one call is used to quickly download all the mail and another later call is used to send any replies. Thus with POP3 a user might have two 1 minute calls before and after a 30 minute e-mail session instead of keeping the call for 30 minutes with IMAP2, and each phone line the institution offers could be serving 15 times as many such users who would each pay a lot less in long-distance phone bills. MIME: MIME (Multipurpose Internet Mail Extensions) is a relatively new standard Internet for the format for messages with multiple parts, and with non-ASCII data. Any client that can import or export files can use MIME in a clumsy way if you have a program to create and/or decode a MIME message. Some clients have built-in features to do this. Client-server mail protocols generally only deal with entire messages, and can retrieve MIME messages as well as any other messages since MIME was carefully designed to be transparent to existing mail systems. However, IMAP4 has features to allow retrieval of individual parts of MIME-encoded messages. The chart below lists whether a package has MIME support. Servers for protocols that don't offer any special MIME features are marked na for Not Applicable since they need do nothing for users to use MIME. All IMAP4 servers can also do this, but the chart lists whether they include explicit MIME support. More about the protocols: Name: Post Office Protocol, Version 2 Nickname: POP2 Document: RFC 937 (Butler et al, February 1985) TCP-port: 109 Sites: Name: Post Office Protocol, Version 3 Nickname: POP3 Document: RFC 1460 (Rose, May 1993) TCP-port: 110 (109 also often used) Sites: UC Irvine, MIT Name: Distributed Mail Service Protocol Nickname: DMSP, Pcmail Document: RFC 1056 (Lambert, June 1988) TCP-port: 158 Sites: MIT Name: Interactive Mail Access Protocol, Version 2 Nickname: IMAP2 Document: RFC 1176 (Crispin, August 1990) TCP-port: 143 Sites: Stanford, U Washington Name: Interactive Mail Access Protocol, Version 3 Nickname: IMAP3 Document: RFC 1203 (Rice, February 1991) TCP-port: 220 Sites: Stanford Name: Internet Mail Access Protocol, Version 4 Nickname: IMAP4 Document: Draft RFC: draft-ietf-imap-imap2bis-02.txt (Crispin, October 1993) TCP-port: 143 Sites: U Washington Note: The "I" in IMAP used to stand for "Interactive". Now it stands for "Internet". Also, Internet drafts are available at ds.internic.net, munnari.oz.au, and nic.nordu.net in directory internet-drafts. IMAP4 used to be called IMAP2bis. Other sources of similar information: By anonymous ftp from ftp.cac.washington.edu: imap/imap.vs.pop -outlines differences in more detail imap/imap.software -list of IMAP software Mailing lists: pop@jhunix.hcf.jhu.edu imap@cac.washington.edu CW-EMAIL@EARNCC.EARN.NET Implementations: Prot Computer Implementation End MIME Source ------ ---------- ------------------- ---- ---- -------------------------------- DMSP PC pc-epsilon (3.1) clnt ? allspice.lcs.mit.edu DMSP PC pc-netmail (3.1) clnt ? allspice.lcs.mit.edu DMSP PC pc-reader clnt ? allspice.lcs.mit.edu DMSP Unix Pcmail 3.1 reposit. srvr na allspice.lcs.mit.edu DMSP Unix/EMACS Pcmail 4.2 clnt ? allspice.lcs.mit.edu DMSP PC PC/TCP clnt ? FTP Software DMSP OS/2 PC/TCP clnt ? FTP Software DMSP OS/2 TCP/2 clnt ? Essex Systems DMSP OS/2 TCP/2 SERVER PACK srvr na Essex Systems DMSP OS/2 TCP/2 ADV CLIENT clnt ? Essex Systems IMAPx Macintosh MacMS 2.2.1 clnt no sumex-aim.stanford.edu 11/7/93 IMAP24 Macintosh Mailstrom 1.04 clnt no sumex-aim.stanford.edu 11/7/93 IMAP24 Macintosh Mailstrom 2 (b?) clnt yes sumex-aim.stanford.edu 10/19/93 IMAP2 Macintosh PathWay clnt no The Wollongong Group 2/25/94 IMAP2 Unix/X PathWay clnt no The Wollongong Group 2/25/94 POP3 Macintosh PathWay clnt no The Wollongong Group 2/25/94 POP3 Unix/X PathWay clnt no The Wollongong Group 2/25/94 IMAP? Macintosh ECSMail Mac (alpha) clnt yes ISA 11/7/93 POP2 Macintosh MacPOP 1.5 clnt ? trident.arc.nasa.gov POP2 MS-DOS PC POP 2.1 clnt ? trident.arc.nasa.gov POP3 Macintosh TCP/Connect II clnt ? InterCon Systems Corporation POP3 NeXT EasyMail clnt yes ftp.cac.washington.edu 11/7/93 IMAP2 NeXT MailManager srvr yes ftp.cac.washington.edu 11/7/93 IMAP2 TOPS20 MAPSER srvr na ? 11/7/93 IMAP2 Unix imap kit srvr na ftp.cac.washington.edu 2/1/94 POP23 Unix imap kit srvr na ftp.cac.washington.edu 2/1/94 IMAP2 Unix Pine 3.88 clnt yes ftp.cac.washington.edu 12/7/93 IMAP? VMS Pine ? port clnt ? vms.huji.ac.il 2/25/94 IMAP? VMS ImapD port srvr ? vms.huji.ac.il 2/25/94 POP3 Macintosh Eudora 1.3.1 clnt ? ftp.qualcomm.com 11/2/93 POP3 Macintosh Eudora 1.4 clnt ? ftp.qualcomm.com 11/2/93 POP3 Macintosh Eudora 1.4.1 (beta) clnt ? ftp.qualcomm.com 1/28/94 POP3m Macintosh Eudora 2.0 (in dev) clnt ? Qualcomm POP3 MS-WINwf Eudora 1.0.1 clnt ? ftp.qualcomm.com 9/21/93 POP3 MS-WINw Eudora 1.4b17 clnt ? ftp.qualcomm.com 11/2/93 POP3 MS-WINw Eudora 2.0a14 clnt ? Qualcomm 11/2/93 IMAP2 Unix imapd 3.1/Stanf srvr na sumex-aim.stanford.edu* IMAP24 Unix imapd/UWash srvr ? ftp.cac.washington.edu 11/7/93 IMAP2 Unix/X Ximap 0.7.2 clnt ? sumex-aim.stanford.edu IMAP? Unix/X XLView 1.22 clnt yes sumex-aim.stanford.edu IMAP? Unix/X Palm (in dev) clnt ? UMiami 11/7/93 IMAP? Unix/X Cyrus (in dev) clnt yes CMU 11/7/93 IMAP2 MS-DOSl+ PC-Pine 3.88 clnt yes ftp.cac.washington.edu 1/25/94 IMAP? Xrx Lsp Mc MM-D clnt no Stanford U 11/7/93 IMAP? Xrx Lsp Mc Yes-Way clnt yes Stanford U 11/7/93 IMAP2 MS-WINw ECSMail 2.1 clnt ? ISA, ftp.srv.ualberta.ca 2/25/94 IMAP2 MS-WINw ECSMail 2.2 (beta) clnt yes ISA, info.asu.edu 2/25/94 IMAP2 Unix/XM ECSMail Mo (in dev) clnt yes ISA 11/7/93 IMAP2 MS-DOS ECSMail DOS(in dev) clnt yes ISA 11/7/93 IMAP? Unix UMAIL clnt no umail@umail.umd.edu 11/7/93 IMAP? Unix MS clnt no ftp.cac.washington.edu 11/7/93 IMAP2 MS-WIN PathWay clnt no The Wollongong Group 2/25/94 POP3 MS-WIN PathWay clnt no The Wollongong Group 2/25/94 IMAP2 MS-WIN WinPine (proposed) clnt yes U Washington 11/7/93 IMAP? NT ECSMail 2.1 clnt yes ISA, ftp.srv.ualberta.ca 11/7/93 IMAP? OS/2 ECSMail OS/2(in dev)clnt yes ISA 11/7/93 IMAP2 Amiga Pine 3.8x (in dev) clnt yes UWashington 11/7/93 POP23 Macintosh POPMail 2.09 clnt ? boombox.micro.umn.edu 12/3/93 IMAP2 Macintosh POPMail 2.09 clnt ? boombox.micro.umn.edu 12/3/93 POP2 Macintosh MailStop 1.1.3 srvr na boombox.micro.umn.edu 1/18/94 POP2 MS-DOS LifeLine Mail 2.0 clnt ? SunSelect 12/7/93 POP23 MS-DOS SelectMail 2.1 clnt ? SunSelect 1/25/94 POP2 MS-DOSk ? srvr na ucsd.edu POP2 MS-DOSk net091b srvr na boombox.micro.umn.edu 12/3/93 POP3 MS-DOSk pop3nos v1.86 srvr na boombox.micro.umn.edu 12/3/93 POP3 MS-DOSk pop3serv srvr na biochemistry.crwu.edu POP2 MS-DOS MD/DOS-IP clnt ? U Maryland POP2 MS-DOS PC/TCP clnt ? FTP Software POP2 OS/2 PC/TCP for OS/2 clnt ? FTP Software 11/2/93 POP23 MS-DOSp POPMail/PC 3.2.2 clnt ? boombox.micro.umn.edu 1/11/94 IMAP? MS-DOSp POPMail/PC 3.2.2 clnt ? boombox.micro.umn.edu 1/11/94 POP23 MS-DOSp Minuet 1.0 (beta) clnt ? boombox.micro.umn.edu 1/11/94 POP? MS-WINls TCPMail clnt ? Pinesoft (pinesoft@net.com) POP2 Unix U Minn popd 1.5c srvr na boombox.micro.umn.edu 11/19/93 POP2 Unix USC-ISI popd srvr na trident.arc.nasa.gov POP2 Unix imapd/ipop2d srvr na ftp.cac.washington.edu POP23k Unix mh-6.7 (UCI RandMH) both ? ftp.cc.berkeley.edu POP? Unix zmail clnt ? Z-Code Software (info@z-code.com) POP? Unix ?mush clnt ? I heard a rumor 2/4/94 POP23k UnixX mh clnt ? ? POP23k UnixX xmh clnt ? ftp.x.org 2/15/94 POP23k UnixX exmh clnt ? ? POP23k UnixX dxmail/mh clnt ? DEC POP2 VM FAL srvr na IBM POP2 VM ? srvr na Texas Tech University POP? VM ?POPD srvr na vmd.cso.uiuc.edu 2/4/94 POP2 OS/2 TCP/2 SERVER PACK srvr na Essex Systems POP2 VMS MULTINet srvr na TGV, Inc. POP2 HP3000/MPE NetMail/3000 srvr na 3K Associates POP3k Macintosh Eudora X clnt ? ftp.brown.edu POP3 Macintosh MacPOP (Berkeley) clnt ? ftp.cc.berkeley.edu POP3k Macintosh TechMail 2.0 clnt ? net-dist.mit.edu POP3 Macintosh MacMH clnt ? jessica.stanford.edu/info POP3 Macintosh VersaTerm Link clnt ? Synergy Software 10/8/93 POP3 Macintosh LeeMail 2.0.2 (shw) clnt ? chs.cusd.claremont.edu 10/12/93 POP3 Mac7pro Mail*Link Internet clnt yes StarNine Technologies 2/18/94 POP3t Unix popper-1.7 srvr na ftp.cc.berkeley.edu 10/15/93 POP3k Unix popper-1.7k srvr na ftp.brown.edu POP3 Unix popper-1.831 srvr na ftp.cc.berkeley.edu 11/3/93 POP3 Solaris2.X popper-1.831/uore srvr na ftp.uoregon.edu 10/19/93 POP3 Unix popper-1.831/qual srvr na ftp.qualcomm.com 11/16/93 POP3 Unix popper-1.8u2Q1/Q2 srvr na ? 1/11/94 POP3k Unix mh-6.7 (UCI RandMH) both ? ics.uci.edu POP3 Unix imapd/ipop3d srvr na ftp.cac.washington.edu POP3 Unix pop3d 1.004 srvr na ftp.ucdavis.edu 12/3/93 POP2 Unix pop2d 1.001 srvr na ftp.ucdavis.edu 12/3/93 POP3 Unix mush 7.2.5 clnt ? ? 1/4/94 POP3t MS-DOSnpo PC/TCP clnt ? FTP Software POP3 OS/2 PC/TCP for OS/2 clnt ? FTP Software 11/2/93 POP3 MS-DOS TechMail(future) clnt ? ? POP3 MS-WINl TechMail for Wind. clnt ? net-dist.mit.edu 2/25/94 POP3 OS/2l TechMail for Wind. clnt ? net-dist.mit.edu 2/25/94 POP3 MS-DOS ? clnt ? logos.ucs.indiana.edu POP3 MS-DOSp NUPop 1.03 clnt no ftp.acns.nwu.edu 11/5/93 POP3 MS-DOSp NUPop 2.02 clnt no ftp.acns.nwu.edu 1/18/94 POP3 MS-DOSp NUPop 2.1 (alpha) clnt yes ftp.acns.nwu.edu 2/25/94 POP3 MS-WIN Pceudora clnt ? ftp.qualcomm.com 9/24/93 POP3 MS-WINw WinPMail 1.1 (test) clnt no David Harris 11/15/93 POP3 ? POPgate (Pmail gw) clnt ? risc.ua.edu 9/24/93 POP3 MS-DOSl PMPOP (Pmail gw) clnt ? risc.ua.edu 10/20/93 POP3x MS-WIN WinQVT (2.1) clnt ? QPC Software (shareware) POP3 MS-WINp wnqvtnet 3.0 clnt ? ftp.cica.indiana.edu POP3 MS-WINp wnqvtnet 3.9 clnt ? ftp.cica.indiana.edu 2/1/94 POP3 MS-WIN Open Systems Mail clnt ? Pine Software POP3 VMS IUPOP3 (1.7) (1.6?) srvr na logos.ucs.indiana.edu POP3 VMS MULTINet both ? TGV, Inc. POP3 VMS PMDF 4.2 srvr na Innosoft 1/7/94 IMAP? VMS PMDF 4.2 srvr ? Innosoft 11/7/93 IMAP? MS-DOS PMDF E-mail Interc clnt ? Innosoft 3/2/94 IMAP? Macintosh PMDF E-mail Interc clnt ? Innosoft 3/2/94 POP3 OS/2 TCP/2 SERVER PACK srvr na Essex Systems POP3 OS/2 TCP/2 ADV CLIENT clnt ? Essex Systems POP? MS-DOS UCDmail clnt ? ucdavis.ucdavis.edu POP? MS-DOS PC POP clnt ? ?Bill Schweickert/Sterling Fed POP23 MS-WINnpo Super-TCP for W e.0 clnt yes Frontier Technologies 1/4/94 POP? MS-WIN Windows ELM clnt ? lister.cc.ic.ac.uk 11/2/93 POP23 MS-DOSni ChameleonNFS both ? NetManage POP23 MS-DOSni Chameleon beta clnt yes NetManage POP? Macintosh MEWS clnt ? ? POP? Macintosh byupopmail clnt ? ? POP? VM ? srvr na TTUVM1 ? Macintosh Hypermail ? ? ? ? OS/2 lamailpop ? ? ftp-so2.cdrom.com POP3 MS-DOSs pcelm clnt ? lister.cc.ic.ac.uk 1/25/94 POP3 MS-WINs winelm clnt ? lister.cc.ic.ac.uk 1/25/94 POP3 Netware Mercury 1.11 srvr na risc.ua.edu 2/4/94 POP3 MS-WINw gmail (in test) srvr na ftp.usma.edu 2/25/94 POP3 MS-Windows Pegasus/Win 1.13(b) clnt yes ? 3/9/94 ------ ---------- ------------------- ---- ---- -------------------------------- Appendix: Some other packages for desktop systems ------ ---------- ------------------- ---- ---- -------------------------------- ? MS-DOSs CMM peer ? Cinetic Systems 1/25/94 ? MS-DOSs WinMail 1.1a peer ? Obsolete SMTP Macintosh LeeMail 1.2.4 peer ? Shareware, laf@mitre.org SMTP Macintosh LeeMail 2.0.2 (shw) peer ? chs.cusd.claremont.edu 10/12/93 SMTP MS-DOSni ChameleonNFS peer ? NetManage 2/25/94 uucp Macintosh FernMail peer ? Shareware, dplatt@snulbug.mtview.ca.us prop Macintosh MacPost both ? ftp.lu.se 10/19/93 uucp Macintosh Eudora 1.3.1 peer ? ftp.qualcomm.com uucp Macintosh UUPC peer ? dplatt@snulbug.mtview.ca.us uucp Macintosh gnuucp peer ? jim@fpr.com uucp MS-DOS waffle peer ? ? uucp MS-DOS UUPC peer ? ? fshare MS-Windows Pegasus/Win 1.02 clnt ? risc.ua.edu 12/3/93 fshare MS-Windows Pegasus/Win 1.13(b) clnt yes ? 3/9/94 fshare MS-DOS Pegasus/DOS 3.01 clnt yes risc.ua.edu 12/3/93 fshare Macintosh Pegasus/Mac 2.04 clnt ? risc.ua.edu 10/5/93 SMTP MS-DOS Charon gway ? risc.ua.edu 10/15/93 Waffle MS-WIN Boxer clnt ? ftp.halcyon.com 12/3/93 ? MS-? pcelm clnt ? simtel 12/3/93 ? MS-? elm-pc clnt ? lister.cc.ic.ac.uk 12/3/93 SMTP MS-WINw Internt Ex for cc:m gway yes IMA 1/31/94 SMTP Netware Mercury 1.11 gway ? risc.ua.edu 2/4/94 ? Macintosh PowerMail clnt ? Apple 2/18/94 SMTP OS/2 PC/TCP v1.3 peer ? FTP Software 2/18/94 fshare MS-DOS? Microsoft Mail clnt ? Microsoft 3/2/94 ? Macintosh Microsoft Mail clnt ? Microsoft 3/15/94 fshare DOSWINMac cc:mail clnt ? Lotus 3/15/94 MHS/G DOSWINMac DaVinci eMAIL clnt ? DaVinci 2/24/94 P7uucp DOSWINMac OpenMail clnt ? HP 3/2/94 ? DOSWINMac WordPerfect Office clnt ? WordPerfect Crop. 3/15/94 ? DOSMac MailWorks clnt ? DEC 3/2/94 MHS/G DOSWIN BeyondMail 2.0 clnt ? Beyond, Inc./Banyon 3/2/94 ? DOSWINMac Quickmail 2.6 clnt ? CE Software 3/15/94 ? DOSWINMac Lotus Notes clnt ? Lotus 3/15/94 ? Macintosh FirstClass clnt ? Softarc 3/15/94 ------ ---------- ------------------- ---- ---- -------------------------------- Other issues: (1) What are the common extensions to POP3 and which clients/servers support them? POP3k - Kerberos POP3a - AFS Kerberos POP3x - ? POP3t - xtnd xmit facility--allows client to send mail through additional POP commands, thus allowing server to verify/log source of mail. (2) What DOS protocol stacks are supported? MS-DOSm - Lan Manager MS-DOSn - NDIS Drivers MS-DOSl - Lan Workplace for Dos MS-DOSs - Sun PCNFS MS-DOSp - Packet Drivers MS-DOSo - ODI Drivers MS-DOSi - IPXLink MS-DOSf - FTP Software PC/TCP MS-DOSk - KA9Q I think MS-WIN? - similar MS-WINw - WinSock compliaint (3) Other notes IMAPx - MacMS's own dialect of IMAP. IMAP24 - IMAP2 or IMAP4 fshare - uses file sharing. Unix/X - X Windows based Unix/XM - Motif based ------ ----------- ------------------- ------- --------------------------------