mrc@Tomobiki-Cho.CAC.Washington.EDU (Mark Crispin) (01/03/91)
Archive-name: mail/imap/imap/1991-01-02 Archive: ftphost.cac.washington.edu:/imap/imap.tar.Z [128.95.112.1] Original-posting-by: mrc@Tomobiki-Cho.CAC.Washington.EDU (Mark Crispin) Original-subject: Re: POP protocol Reposted-by: emv@ox.com (Edward Vielmetti) In article <E9633327E93FE1EE45@vaxsar.bitnet> BIWINE@VAXSAR.VASSAR.EDU (Bill Wine) writes: >Our concern is that the POP architecture >may not be sutiable for a large mail system. It seems inefficient for >the POP client to check for newmail every 5 or 10 minutes. >It seems to me that a >better idea would be for a client to log in once, and for the server >to check for newmail periodically, then send it to the client. There is no way that I am aware of in either the POP2 or the POP3 protocol for a client to check for new mail; the only way is to close the POP connection and open a new one. There are some auxillary protocols to "check for new mail", some of which I believe are UDP based. >Would anyone care to share their experiences with large Mac or PC >e-mail systems (100+ concurrent users). Is the POP architecture >suitable for large systems? Is there a better one? An alternative to the POP protocols is the IMAP protocol (RFC-1176). IMAP provides both an explicit "check for new mail" and server- controlled new mail notification. You can get a distribution package on FTPHOST.CAC.WASHINGTON.EDU (IP address 128.95.112.1) as imap/imap.tar.Z via anonymous FTP. Stanford has written a Mac client. I wrote a NeXT and generic Unix client; I'm working on a PC client for IMAP now. The IMAP distribution also includes a POP2 and POP3 server so you can leverage on your existing POP software without incompatibilities (the underlying mail access library is the same in all cases); the POP servers can also be IMAP clients so any POP clients can access IMAP servers. Whether you choose IMAP or POP depends a lot upon what you are trying to do. They are often mistakenly thought of as competing protocols, but really have different functionalities. POP is for downloading an RFC-822 format mailbox to a client, whereas IMAP is for a client to manage and retrieve data on a remote mailbox maintained on a server. _____ | ____ ___|___ /__ Mark ("Gaijin") Crispin "Gaijin! Gaijin!" _|_|_ -|- || __|__ / / R90/6 pilot, DoD #0105 "Gaijin ha doko?" |_|_|_| |\-++- |===| / / Atheist & Proud "Niichan ha gaijin." --|-- /| |||| |___| /\ (206) 842-2385/543-5762 "Chigau. Omae ha gaijin." /|\ | |/\| _______ / \ FAX: (206) 543-3909 "Iie, boku ha nihonjin." / | \ | |__| / \ / \MRC@CAC.Washington.EDU "Souka. Yappari gaijin!" Hee, dakedo UNIX nanka wo tsukatte, umaku ikanaku temo shiranai yo.