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00README.NOW.OR.SUFFER 14-Sep-2002 14:20 1k
INSTALL 14-Sep-2002 14:22 50k
INSTALL.html 14-Sep-2002 14:20 56k
authlib.html 09-Sep-2002 14:29 38k
authmysql.html 09-Sep-2002 14:25 4k
authmysqllib.c 14-Sep-2002 14:26 19k
courier-install.html 09-Sep-2002 14:29 50k
Courier-IMAP - logo by Bas Boudrie <bboudrie@hetnet.nl>
Copyright 1999-2002, Double Precision, Inc. This software is
distributed under the terms of the GNU General Public License. See
COPYING for additional information.
Courier-IMAP is a server that provides IMAP access to Maildirs. This
IMAP server does NOT handle traditional mailbox files
(/var/spool/mail, and derivatives), it was written for the specific
purpose of providing IMAP access to Maildirs.
"Maildir" is a directory-based mail storage format originally
introduced in the Qmail mail server, and adopted as an alternative
mail storage format by both Exim and Postfix. Courier-IMAP is popular
on Qmail/Exim/Postfix sites that are configured to use maildirs. The
primary advantage of maildirs is that multiple applications can access
the same Maildir simultaneously without requiring any kind of locking
whatsoever. It is a faster and more efficient way to store mail. It
works particularly well over NFS, which has a long history of
locking-related woes.
This is the same IMAP server that's included in the Courier mail
server, but configured as a standalone IMAP server that can be used
with other mail servers - such as Qmail, Exim, or Postfix - that
deliver to maildirs. If you already have Courier installed, you do not
need to download this version. If you install this version, you must
remove it if you later install the entire Courier server. It's
possible to have both versions installed, but this will require a
delicate juggling act that you'll have to learn on your own.
Courier-IMAP implements several extensions to the basic Maildir mail
storage format in order to support some additional features, such as
folders and "soft" quotas. This is done in a way that's backwards
compatible with the standard Maildir users (although, of course, they
will ignore the additional features). Other software that understands
and uses the same Maildir extensions is SqWebMail, and maildrop.
Features
* Extremely small footprint. On x86, Courier-IMAP's main daemon is a
fraction of the size of the UW-IMAP server, and has a greatly
reduced memory footprint.
* Abstract authentication modules. Authentication of login userid
and password is wrapped up into a completely stand-alone module.
Several modules are provided to authenticate using the traditional
password/shadow files, via the PAM library, from a table on a
MySQL server, or from an LDAP server (requires MySQL or OpenLDAP).
An experimental authentication module for PostgreSQL is also
available. You can also write your own custom userid/password
validation program. A "custom" authentication module is included,
which authenticates absolutely nothing. Add your own code to it in
order to implement a site-specific authentication mechanism.
* Virtual mailboxes. The userdb authentication module uses either a
GBDM or DB database to map arbitrary userids to maildirs. Perl
scripts are included to manage this database. There's also an
authentication module that implements the vpopmail virtual mailbox
implementation.
* Ability to restrict the maximum number of IMAP logins, and the
maximum number of logins from the same IP address. This will
prevent denial-of-service attacks where the attacker attempts to
overload the server with multiple login connections.
* Shared folders. With additional server-side setup, folders can be
shared between groups of accounts.
* IMAP over SSL. If OpenSSL is installed, Courier-IMAP will,
optionally, accept IMAP connections over SSL. The IMAP STARTTLS
extension is also implemented.
* IPv6 support, if available.
* IMAP extensions that implement server-side sorting. This can be
optionally disabled in environments that have limited resources.
* Optional support for sorting and searching in non-English
character sets. Non-English character set tables are optional, and
will not take up any additional overhead unless they are
specifically included. Download the source code to obtain a list
of currently supported character sets.
* A compatible POP3 server is also included in the Courier-IMAP
package, that uses the same authentication modules. The POP3
server can only access the INBOX, and cannot access any folders.
The overall design goal of Courier-IMAP is to provide IMAP services to
maildirs with the least amount of resources. For this reason there are
many parameters that can be tuned during initial configuration and at
runtime. Unwanted components can be removed completely, and they will
not take up any resources. Few sites need the ability to search
messages in twenty different character sets, so there's no need to
waste memory storing large character set mapping tables. Sites that
need multilingual searching and sorting abilities can selectively
choose which character set tables will be supported by the server,
individually. If SSL support is needed, it is available. If not, the
SSL wrapper does not have to be installed at all. If the server does
not have the sufficient resources to sort large folders, the
server-based IMAP sorting function can be turned off.
Download
Download Courier-IMAP from
http://www.courier-mta.org/download.php#imap
CVS Repository
The source code of the standalone Courier-IMAP version is also
available from an anonymous CVS repository. See
http://courier.sourceforge.net/status.html for more information.
Mailing list
Subscribe to the courier-users mailing list from
http://lists.sourceforge.net/mailman/listinfo/courier-users, or send a
message to <courier-users-request@lists.sourceforge.net> and put
"subscribe" in the subject line.
This mailing list does not accept mail from non-subscribers. You must
subscribe to the list before sending any messages.
RPM installation notes
It is possible to create binary RPM packages directly from the source
code tarball. A source RPM is not required. RPM 3.0.3 or higher is
required. IMPORTANT: even though building an RPM saves you the
headaches of manually compiling the code, you should still read the
INSTALL file as it contains many important details you need to know.
Just as the source cannot be compiled by root, the Courier-IMAP RPMs
cannot be built as root either. However, by default, RPM is not
configured to be used for building software as a non-root user. It
will be necessary to make some minor changes to the RPM configuration
to enable building as a non-root user. See the FAQ for more
information.
To build a binary RPM package, enter:
rpm -ta courier-imap-1.5.3.tar.gz
This builds the following packages:
* courier-imap - the base package.
* courier-imap-ldap - subpackage that includes support for
authenticating from an LDAP directory.
* courier-imap-mysql - subpackage that includes support for
authenticating from a MySQL database.
* courier-imap-pgsql - subpackage that includes support for
authenticating from a PostgreSQL database.
The INSTALL file in the Courier-IMAP package contains additional
information about LDAP, PostgreSQL and MySQL authentication. If the
build system does not have the required libraries (see INSTALL for a
list of requirements), these subpackages will be empty.
NOTE: The binary RPM will not install if you use a PAM library and
have another IMAP or a POP3 server installed. The binary RPM installs
its own /etc/pam.d/imap and /etc/pam.d/pop3 configuration files, which
are likely to conflict with the PAM configuration file from another
IMAP or POP3 server. If you previously installed another IMAP or a
POP3 server without using RPM, Courier-IMAP will successfully install
and immediately overwrite your existing /etc/pam.d/imap and
/etc/pam.d/pop3 files.
On systems that use inetd (such as Red Hat 6.2 or earlier), you will
also have to manually delete the imap and pop-3 entries from
/etc/inetd.conf as well. Courier-IMAP listens for client connections
by itself. It doesn't need inetd, and you need to tell inetd to
release that port.
On systems that use xinetd (such as Red Hat 7.0 and later), any xinetd
entries for imap and pop3 ports must be disabled.
If the default options in the RPM build need to be changed, proceed as
follows:
Copy courier-imap-1.5.3.tar.gz to your %{_topdir}/SOURCES directory,
extract the file courier-imap.spec, then copy it to your
%{_topdir}/SPECS directory. Make your custom changes to the spec file,
then run "rpm -bb courier-imap.spec".
Also - if you are upgrading from the 0.14 or 0.15 RPMs, you may have
to run the following command after upgrading from 0.14 or 0.15:
/sbin/chkconfig --add courier-imap.
Documentation
The following documentation is included in the Courier-IMAP
distribution. It is presented here for your convenience.
* README: Installation and some general documentation
* FAQ: Frequently Asked Questions
* README.imap: Hints on configuring IMAP clients
* authlib: Documentation on the authentication library used by
Courier-IMAP. You want to read this if you would like to write
your own authentication modules.
* README.maildirquota: Enhancements by Courier-IMAP to the
traditional Maildir format, and README.sharedfolders: How
Courier-IMAP implements shared folders. These documents describe
how Courier-IMAP implements various features that are not a part
of the traditional maildir mailbox.
* BUGS: known bugs.
Links
The book Postfix talks about configuring the Postfix mail server to
deliver to Maildirs, for Courier-IMAP.
Courier-IMAP + Maildrop + QMail with Virtual Domains HOWTO - self
explanatory.
Install and Test Qmail with POP, IMAP and WebMail - a step by step
tutorial on setting up a turn-key mail server.
http://www.gallowglass.org - how to setup your own private CA and then
generate signed SSL certs for POP and IMAP over SSL.
Qmail FreeBSD toaster - another step by step tutorial, this one is
based on FreeBSD.
Qmail VMailMgr and Courier-IMAP HOWTO - extensive documentation on
integrating Courier-IMAP with the Qmail mail server and the VMailMgr
virtual domain manager.
A patch to use DRAC with Courier-IMAP is available at
http://aelyn.hell-city.org/courier-imap-popd-drac.patch.
SecurityFocus's article titled "Clear Text Communication: Slaying the
Beast Part II" talks about general issues concerning E-mail and
security. Courier-IMAP is briefly mentioned in this article.
_________________________________________________________________
Sam Varshavchik <mrsam@courier-mta.com>