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qmail by John Levine

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Picking Up Mail with IMAP and Web Mail

Although POP is by far the most common way for users to collect their mail, many mail servers also offer IMAP and web mail. IMAP is conceptually similar to POP except that the client program has a full set of tools to manipulate the mailbox on the server. The advantage of IMAP over POP is that the mailbox remains on the server, so the user can use different mail programs from different locations, seeing consistent mailbox contents at all times. While qmail provides no IMAP server of its own, the IMAP server from the Courier mail package uses Maildirs as its mailbox format and works well with qmail. I describe its setup below.

Web mail provides access to a mailbox using a web browser as the mail client. Many web mail packages are available on the Net that use POP or IMAP to access the user mailboxes. They're not specific to qmail, so I don't describe them here. The Courier package includes a web mail component called SqWebMail that uses Maildirs as its mailbox format. I describe its installation later in this chapter.

Maildirs don't have to be locked while a client reads or updates them, so the POP and IMAP servers and SqWebMail can access the same mailbox simultaneously without trouble. Systems based on mboxes can't do that. I routinely have my mailbox open in pine on a BSD system, Pegasus and Opera 7 on a Windows laptop, and SqWebMail on a web browser, all at the same time without any trouble. You can download the sources for Courier IMAP and ...

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