Friday, May 10, 2002 07:31 AM
Go to a reference like the IMAP.org site and do some reading.
POP3 is an older protocol, for working with one single mail store/ "mailbox"/"inbox folder", transferring messages from server to client, to update the client's copy, keeping it up to date with the server's copy.
IMAP is more comprehensive, and actually includes POP3 functionality as a subset, but can also do other things.
IMAP can work with multiple mail stores ("mailboxes", "sets of folders", etc. whatever they are called, even "bboards", "newsgroups" etc., some places even gateway Usenet newsgroups, to be served as public shared IMAP folders), on multiple servers, also local as well as remote mail stores (so you can have some sets of folders just stored local on the client, others on server A, still others on server B, and with one IMAP client (if it's written correctly) you can check mail, read & delete messages etc., independently in all of them, without them getting mixed up), and can synchronize local mail stores on the client, with mail stores on the server, like if you go offline, edit your mail, reading & deleting messages, and then come back to synchronize.
Also if you are going to have multiple clients sharing the same mail store/mailbox on a server, IMAP is better than POP, because POP only has one concept of read vs unread for one single client (and the nonstandard, optional UIDL extension for the client to ask the server which messages are there, which are new and which it has seen before), but IMAP has support for generalized flags on messages, so multiple clients could all independently maintain different states, of which messages they have read vs. which are still unread, etc. in the same folder.
Both POP3 and IMAP are strictly for "reading" mail, not for "sending" mail (you need ESMTP/STMP for sending), though POP3 has its optional, nonstandard "XTEND XMIT" function which can send mail, given the right client (just Eudora?) and the right POP server (just Qualcomm/Eudora's pop server?).