"Fossies" - the Fresh Open Source Software archive 
Courier-IMAP
For a general introduction and configuration settings for some popular
IMAP clients, go and read imap/README(.html).
In this document:
* Requirements
* Upgrading
* Installation
* Account initialization hook
* Using shared folders
* CRAM-MD5 Authentication
* Certificate Authentication
* Sending mail via an IMAP connection
* Realtime folder status updates
* Account OPTIONS
* SMAP
Requirements
Now is the good time to read the FAQ, before you start. The FAQ is located
in the file imap/FAQ(.html?).
* C++ compiler - A C++ compiler is required. The server is written in C,
but there are some configuration scripts that use C++ code.
* make - The GNU make is recommended. Solaris's make is to be avoided.
xBSD already has a gmake port, install it and use it (use gmake
everywhere this document refers to make).
* GDBM/DB - either the GDBM or the Berkeley DB library is required.
* The GNU IDN library (http://www.gnu.org/software/libidn/).
* Gamin (http://www.gnome.org/~veillard/gamin/) or FAM
(http://oss.sgi.com/projects/fam/) -- either one -- is optional. If
Gamin or FAM is installed, it is used for an enhanced IMAP IDLE
implementation that provides real-time folder status updates to
concurrent IMAP clients that have the same folder opened.
* The Courier authentication library. Before installing Courier-IMAP,
download and install http://www.courier-mta.org/authlib/.
UPGRADING
Upgrading from Courier-IMAP 4.9.3, and earlier
In 5.0.0, the IMAP server resets the epoch for an internal sequence number
generator for new mailboxes. This is an internal attribute of individual
IMAP folders, that's defined by the IMAP specification. Each folder in a
mailbox carries an individual sequence number, it is defined as a 32 bit
integer value, and required to be a monotonically increasing value. and
RFC 2060 recommended that "... a good value to use for the unique
identifier validity value is a 32-bit representation of the creation
date/time of the mailbox."
On modern platforms, the system time is now a 64 bit value (even on the
remaining 32 bit platforms). With Y2038K on the horizon, it's time to
reset the epoch (the new epoch, for anyone who cares, runs until the year
2069). The upgrade impact on existing systems is as follows.
There is no impact on existing folders in existing mailboxes. New folders
will have their internal sequence number in the new epoch.
One potential issue exists if a folder gets deleted by the IMAP client,
and then recreated later. The new folder will now get a lower sequence
number. Although this is technically not allowed, it's unlikely to cause
problems with most IMAP clients. If the same IMAP client deletes and
recreated the mailbox, the client should be completely up to speed. If,
however, there's an IMAP client that accesses the same folder, and some
other IMAP client deletes and recreates the same folder, this might cause
confusion. Most IMAP clients are likely to recover automatically; most
IMAP clients only care that the new sequence number they see is different
from the previous one, in order to trigger a full resynchronization with
the server. In case an IMAP client fails to resynchronize, the remedy is
to remove the IMAP account configuration from the client, and add it back
in.
Copying a mailbox by directly copying the files in maildirs preserves each
folder's epoch. However if a mailbox gets migrated by copying its contents
over IMAP, the folders on the destination IMAP server will not necessarily
have a monotonically higher value -- neither does IMAP guarantee that
different IMAP servers must be in agreement with each other on the subject
of sequence numbers -- and if IMAP clients are repointed to a new server
they may experience problems opening existing mailboxes. To remedy this
situation it will be necessary to completely remove and then reconfigure
the IMAP account, in the IMAP client. Again, verbatim copying of maildirs
has no issues.
A marginal situation exists where if a server completely runs of disk
space, or if there's a hardware failure, and the IMAP server is unable to
retrieve or save an existing folder's sequence number, and must now start
afresh and generate a new one, the IMAP server running on a new epoch will
recover with a lower sequence than the one that existed before. The
rememdy is the same: remove the IMAP account configuration from the
client, and then recreate it.
Upgrading from Courier-IMAP 3, and earlier.
Beginning with 4.0, the authentication library that used to be a part of
Courier-IMAP's source has been spun off into a standalone authentication
library.
You must download and install the Courier Authentication Library from
http://www.courier-mta.org/authlib/ before upgrading. Review the
documentation in the courier-authlib package for more information.
After upgrading to 4.0, or later, to avoid future confusion the old copies
of these configuration files (including the .dist files), should be
removed from Courier-IMAP's configuration directory. They now live in
Courier-authlib's configuration directory (/usr/local/etc/authlib, or
whatever was specified to Courier-authlib's configure script).
Upgrading from Courier-IMAP 1.7.3, and earlier.
After upgrading from Courier-IMAP 1.7.3, or earlier, any existing mail in
POP3 mailboxes may show up as new mail, by some mail clients. Other mail
clients may end up downloading a second copy of any message that was left
in the mailbox before the upgrade. This is a one-time event. Courier-IMAP
2.0.0 uses a different mechanism for generating POP3 message identifiers.
Mail clients that use POP3 identifiers will behave as if all messages,
that were left in the POP3 mailbox before the upgrade, were removed, and
replaced by new messages that happen to be the same content. Depending on
how the POP3 mail client works, it will either flag all messages in the
mailbox as unread, or download a second copy of the message.
Upgrading from Courier-IMAP 1.3.0, and later versions, is a
straightforward process. Follow the instructions in the INSTALLATION
section, below, to install the new version. The "make install-configure"
command automatically preserves the existing system configuration.
However, note that new versions of Courier-IMAP will often introduce
additional configuration options. After make install-configure a cursory
inspection of configuration files in /usr/lib/courier-imap/etc (the
default location of the configuration directory) is recommended, in order
to identify any new configuration settings that might need adjustment.
Upgrading from Courier-IMAP 1.3.8.2 and earlier
The default configuration options have slightly changed. The default
configuration script will now always build the authdaemon module, and
build all real authentication modules inside authdaemond. This is true
even with the authvchkpw module.
Upgrading from Courier-IMAP 1.2.3 and earlier
Courier-IMAP 1.3.0 introduced a new configuration file format that allows
configuration files to be automatically upgraded. Additionally, several
existing configuration files have been renamed in order for their names to
be consistent with the Courier build:
Courier-IMAP < 1.3 Courier-IMAP 1.3.0
-------- ---------
imapd.config imapd
imapd-ssl.config imapd-ssl
pop3d.config pop3d
pop3d-ssl.config pop3d-ssl
The NEWS file has a detailed explanation of how configuration files are
now installed. Basically, make install now installs configfilename.dist,
and make install-configure copies configfilename.dist to configfilename,
becoming the actual configuration file. If there is an existing
configfilename, the old settings in configfilename which are still valid
will be kept in the new configfilename.
This only works as long as both the old and the new configuration files
are in the new format, so this will actually take effect with your next
upgrade Courier-IMAP. If the previous installed version of Courier-IMAP
did not use the new format for configuration files (1.2.3 and earlier),
the old configuration file is backed up to configfilename.bak.
The recommended procedure for upgrading from versions 1.2.3 and earlier is
as follows:
The recommended upgrade procedure is as follows:
* Back up /usr/lib/courier-imap/etc
* Follow the installation procedures, below
* After installing, manually edit all configuration files. Restore, by
hand, any custom configuration settings.
All configuration files are kept in the configuration directory. Nothing
else in /usr/lib/courier-imap is configurable. Do not simply overwrite
1.3.0 configuration files with configuration files from the previous
version. It's tempting, but don't do it. It may work, but you will lose
the automatic upgrade capability for future releases.
Upgrading from Courier-IMAP 1.1 or earlier
Note that Courier-IMAP 1.2 includes a compatible POP3 server, and the
installation script will also install a POP3 server on your system. Even
though it is installed, you are not required to use it, but you still need
to be aware of its existence. If you install the RPM build of
Courier-IMAP, you're going to get the POP3 server started at system boot.
If you do not need POP3 services, edit both the pop3d.config and
pop3d-ssl.config configuration files, and set POP3DSTART and POP3DSSLSTART
to NO
Upgrading from Courier-IMAP 1.0 or earlier
If the server is running, manually stop the server before installing the
new version.
INSTALLATION
To compile and install the Courier-IMAP server (this is the short version,
a longer version follows):
$ ./configure [ options, see below ]
$ make
$ make check # Note - the --enable-workarounds-for-imap-client-bugs
# option to configure will result in make check FAILING.
$ su root
# make install # Or, make install-strip, to strip the executables.
# make install-configure # Install configuration files.
# Start the authdaemond process
NOTE
You MUST run the configure script as normal user, not root. Did you
extract the tarball as root? It won't work. Remove the extracted source
code. Log in as a normal user. Extract the source code as a normal user,
then run configure. You will do everything as a normal user, except for
the final step of installing the compiled software.
NOTE
Courier-IMAP does not use inetd or xinetd. Any inetd or xinetd
configuration settings for the IMAP and POP3 ports must be turned off.
Courier-IMAP will not start if inetd or xinetd is listening for IMAP or
POP3 connections.
--------------------------------------------------------------------------
As mentioned in "Requirements", above, if you are using xBSD, you must use
gmake instead of make.
--------------------------------------------------------------------------
NOTE: The configure script may run as much as 5-10 minutes on slow
machines. It may appear that configure is stuck in a loop, but that's an
illusion. Courier-IMAP is built from a collection of modular components,
each with its own configuration script. The configuration scripts share a
lot of common code, leading to an initial impression that the same
configuration script is being repeatedly run.
See below for a description of the options to the configure script.
WARNING: set your umask to 022 before running make install or make
install-strip.
You should try make install-strip first. Use make install if make
install-strip fails.
The configure script accepts certain options, but the defaults should be
fine most of the time. make install puts everything in
/usr/lib/courier-imap. If the directory /etc/pam.d exists, make install
creates /etc/pam.d/imap and /etc/pam.d/pop3, overwriting any existing
files. If you have some other IMAP server installed, this means that you
will want to save your existing configuration in /etc/pam.d/{imap|pop3}.
"make check" performs some internal sanity checks. If make check fails,
something is wrong, and Courier-IMAP may not work for you reliably.
Certain options are documented to cause make check to fail, due to
different IMAP protocol behavior. If you need to use those options, first
compile Courier-IMAP without them, run make check, and if all goes well
extract the source code again in a different directory, then build it for
the second time using your options.
After installation, you will need to review the files in
/usr/lib/courier-imap/etc and make any changes you deem necessary.
After running make install or make install-strip you will then have to
modify your system's startup scripts to run Courier-IMAP when your system
boots.
Use the following command to start the Courier-IMAP server:
$ /usr/lib/courier-imap/libexec/imapd.rc start
This assumes that Courier-IMAP is installed in /usr/lib/courier-imap. Use
the following command to stop Courier-IMAP:
$ /usr/lib/courier-imap/libexec/imapd.rc stop
You will have to add these commands to your system startup/shutdown
scripts.
IMAP over SSL
To add SSL support you have to install OpenSSL or GnuTLS before installing
Courier-IMAP. Download OpenSSL from http://www.openssl.org/, or GnuTLS
from http://www.gnutls.org.
OpenSSL's support is well-tested, the GnuTLS version is a relatively new
addition, and is considered experimental. Follow OpenSSL's or GnuTLS's
installation instructions, then build Courier-IMAP.
NOTE: Most systems already have an available OpenSSL or GnuTLS package.
Do not build OpenSSL or GnuTLS yourself, if a prebuilt package is
already available. Just install the prebuilt package.
NOTE: The development libraries must be installed in addition to the
runtime package, in order to build Courier-IMAP. On most systems, the
development files (header files, libraries, etc...) are provided in a
separate "devel" package. The base OpenSSL/GnuTLS package is not
sufficient to build Courier-IMAP, the development libraries must be
installed.
The OpenSSL library is selected when both OpenSSL and GnuTLS libraries are
found by the configure script. Use the --with-gnutls option to explicitly
select the GnuTLS library over OpenSSL.
The /usr/lib/courier-imap/etc/imapd-ssl configuration file sets some
additional options for SSL support, which you may need to adjust. Consult
that configuration file for additional information. Then, you also have to
run the /usr/lib/courier-imap/libexec/imapd-ssl.rc script from your system
startup and shutdown scripts, just like the
/usr/lib/courier-imap/libexec/imapd.rc script. You may accept both SSL and
non-SSL connections by running both scripts.
Note that SSL requires a valid, signed, X.509 certificate to be installed
where Courier-IMAP expects to find it. The default location for the X.509
certificate, in PEM format, is /usr/lib/courier-imap/share/imapd.pem. The
X.509 certificate must be signed by a certificate authority that is known
to the IMAP client. You can generate your own self-signed certificate by
running the script /usr/lib/courier-imap/share/mkimapdcert which will work
too, except that IMAP clients using SSL will display a warning message the
first time they connect to the server. To get rid of the warning message
you'll have to pay for a signed X.509 certificate. The gory details of
setting up SSL is beyond the scope of this document, and you should
consult the OpenSSL documentation for more information.
The mkimapdcert script will not overwrite an existing imapd.pem
certificate, in order to allow precompiled packages to simply call
mkimapdcert after installation, without worry.
The bundled POP3 server
The POP3 server included with Courier-IMAP provides POP3 access to INBOX,
and that's about it. Enabling the POP3 server is very similar to enabling
the IMAP server, with the following differences:
The configuration files are /usr/lib/courier-imap/etc/pop3dand
/usr/lib/courier-imap/etc/pop3d-ssl.
The startup/shutdown scripts are /usr/lib/courier-imap/libexec/pop3d.rcand
/usr/lib/courier-imap/libexec/pop3d-ssl.rc.
The SSL certificate is /usr/lib/courier-imap/share/pop3d.pem, and the
/usr/lib/courier-imap/share/mkpop3dcert script can be used to create a
self-signed SSL certificate for testing purposes.
System-V style startup
If your system uses System-V style startup scripts, take a look at
courier-imap.sysvinit - this is a sample /etc/init.d script.
courier-imap.sysvinit is created by configure. In most cases it can be
merely copied to /etc/init.d and /etc/rc?.d directories (with the execute
permission bit turned on).
The sample startup script will check if IMAP or POP3 over SSL is enabled.
The sample startup script automatically creates dummy SSL certificates the
first time it is executed.
Options to configure:
* --prefix=pathname - install here, instead of /usr/lib/courier-imap
* --without-ipv6 - do not compile IPv6 support. The configure
automatically checks if IPv6 support is available, and enables it
automatically. This option suppresses IPv6 support, even if it's
available. IPv6 support means that Courier-IMAP will create an IPv6
socket and accept IPv6 connections. --without-ipv6 should be used if
your system does not fully support IPv6, or if its implementation is
buggy. Most Linux distributions now ship with IPv6 support in glibc,
but without compiling the kernel for IPv6 support. This results in
modprobe regularly complaining in /var/log/messages about the fact
that it can't load the IPv6 module. Use --without-ipv6 to turn off
IPv6 support, if that bothers you.
* --bindir=pathname , --mandir=pathname - override default names of
subdirectories under prefix. See below for more information.
* --with-db=db - Use the DB library instead of the GDBM library You must
have either the GDBM or the DB library installed. If both are present,
GDBM is selected unless you use this option. The GDBM/DB library is
used by Courier for certain functions.
* --with-gnutls - Use the GnuTLS library even if the OpenSSL library is
also installed. Courier-IMAP automatically uses whichever one is
available. The OpenSSL library is selected if both are present. Use
this option to override and select GnuTLS instead.
* --with-piddir=dir - use dir/imapd.pid to store couriertcpd's process
ID.
* --with-userdb=file - use file instead of /etc/userdb (also means that
userdb.dat and userdbshadow.dat are appropriately renamed).
* --enable-workarounds-for-imap-client-bugs - there are a number of
various bugs in certain IMAP clients. The current list of broken IMAP
clients consists of Netscape Messenger and Sun's StarOffice. This
option enables some workarounds for some bugs in these clients,
however, note that this may break compatibility with software that
correctly implements IMAP4rev1. Additionally, "make check" will fail
when this option is used. See imap/BUGS.(html|txt) for more
information. NOTE - if this option is used, make check WILL FAIL. You
should first configure Courier-IMAP without this option, run make
check, then reconfigure Courier-IMAP with this option.
* --with-trashquota - include deleted messages, and the Trash folder, in
the estimated quota usage for maildirs. Quotas are optional, see the
file maildir/README.maildirquota.html for more information. The
default configuration does not count messages marked as deleted (but
not yet expunged) and the contents of the Trash folder (which are
automatically purged by the server) against the quota usage. NOTE - if
this option is used, make check WILL FAIL. You should first configure
Courier-IMAP without this option, run make check, then reconfigure
Courier-IMAP with this option.
* --with-dirsync - after saving a new message to a maildir (the IMAP
COPY and APPEND commands) explicitly sync the maildir's directory
directory. There's a school of thought which believes that the Linux
ext2 filesystem requires the parent directory to be synced, in
addition to the new message file that's just been written to disk.
There's another school of thought that thinks that this issue is
completely blown out of proportion, and is really nothing more than a
tempest in a teapot. However -- to accomodate the former school of
thought -- this option adds a little bit of extra code to sync the
parent directory.
Installation directories
Unless the options --prefix, --bindir, or --mandir are used, everything
will be installed in the directory /usr/lib/courier-imap.
Use the --prefix option to specify a different directory. This directory
will have the following subdirectories:
* etc - configuration files
* bin - binaries
* sbin - superuser binaries
* libexec - additional binaries
* man - manual pages
* share - scripts and data files
* var - temporary files used by the authdaemond, daemon process (if the
authdaemon authentication module is selected).
Having everything installed underneath one directory allows its contents
to be easily backed up, before a newer version of courier-imap is
installed. Reverting to a previous version is as simple as restoring from
backup.
Because some binaries in bin and sbin may be executed from the command
line, it will be necessary to change your systemwide global startup script
to add this directory to the default PATH. Additionally, it will also be
necessary to modify the configuration of the man(1) command so that it can
find Courier-IMAP's manual pages in this directory:
PATH="/usr/lib/courier-imap/bin:$PATH"
if test -w /etc
then
PATH="/usr/lib/courier-imap/sbin:$PATH"
fi
export PATH
MANPATH="/usr/lib/courier-imap/man:$MANPATH"
export MANPATH
As an alternative, you may use the --bindir and --mandir options in order
to install binaries to /usr/local/bin and the manual pages to
/usr/local/man, which should already be searched by default:
./configure --bindir=/usr/local/bin --mandir=/usr/local/man
Other familiar configure options, such as --sysconfdir and --datadir work
too, for those who know how to properly use them.
ACCOUNT INITIALIZATION HOOK
If there is a file or a symbolic link in the maildir called "loginexec",
and if it is executable, then the executable file will be invoked after a
succesful login. If the program terminates with an exit code of 0, the
"loginexec" file (or a symbolic link) will be removed.
USING SHARED FOLDERS
Courier-IMAP supports shared folders. See the file
README.sharedfolders.html for information on how to set up shared folders.
CRAM-MD5 AUTHENTICATION
CRAM-MD5 authentication allows IMAP clients to authenticate themselves
without sending the password in clear-text over the network. Courier-IMAP
now supports CRAM-MD5 by default, but is not enabled for reasons explained
below. CRAM-MD5 support is implemented by the authcram module, with one
exception - authldap, authpgsql, and authmysql support CRAM-MD5
authentication if the LDAP or the MySQL/PostgreSQL server stores
clear-text passwords, and not crypt-ed passwords.
To use CRAM-MD5 it is necessary to use an IMAP client that support
CRAM-MD5 authentication, of course. That's the easy part.
The problem is that it is not possible to use the system password when
logging in using CRAM-MD5. That's because CRAM-MD5 requires the knowledge
of the actual password, in the clear, in order to calculate authentication
tokens (even though that the password itself is not sent in the clear over
the network).
So, implementation of CRAM-MD5 is an advanced task that should be
attempted only when you are comfortable with, and fully understand how
Courier-IMAP works in general. Here's an overview of this procedure:
* Install and implement /etc/userdb, because CRAM-MD5 authentication
uses the /etc/userdb database (but see below for LDAP-specific notes).
* Figure out which accounts are going to use CRAM-MD5 authentication.
People who do not use an IMAP client that supports CRAM-MD5 can
continue and log in with the existing system password. But everyone
who runs a client that supports CRAM-MD5 authentication will need a
new password. Also, it will be necessary to set up CRAM-MD5 passwords
for everyone at the same time. As soon as CRAM-MD5 authentication is
enabled, all CRAM-MD5 enabled clients will attempt to use it. If no
password is available, Courier-IMAP has no choice but to reject the
authentication attempt. Once that happens, the client will correctly
interpret it as an authentication failure (and it is), and the client
will not even try to authenticate using the system password. Use the
following command to assign a CRAM-MD5 password:
userdbpw -hmac-md5 | userdb userdb set hmac-md5pw
Then run the makeuserdb command, as always.
* NOTE: CRAM-MD5 authentication is also be supported by authldap,
authpgsql and authmysql, as long as clear-text passwords are used. See
below for more information. Therefore, if you use LDAP, PostgreSQL, or
MySQL, and you store clear-text passwords, you should all set and
ready to go, and you do not need to install /etc/userdb, as described
in this section.
Enabling CRAM-MD5 authentication
Because of these unfortunate complexities, CRAM-MD5 authentication is
disabled after installation. When you're ready to use CRAM-MD5, edit the
imapd configuration file and add the "AUTH=CRAM-MD5" keyword to the
IMAP_CAPABILITY environment variable, then restart Courier-IMAP. There are
instructions in the imapd configuration file to that effect.
If you do not intend to ever use CRAM-MD5 authentication, you can either
specify --without-authcram option to the configure script, or simply edit
imapd and remove authcram from the AUTHMODULES setting.
CERTIFICATE AUTHENTICATION
Courier-IMAP can use SSL certificates for authentication purposes. For
certificate authentication purposes, one of the fields in your
certificates' subject must match the login ID in the authentication
database. Consider the following certificate:
...
Subject: C=US,ST=New York,L=New York,O=Acme Widgets Inc,CN=John Smith,emailAddress=johnsmith@example.com
If the emailAddress field is configured as the login ID, the
authentication database must provide login details for
johnsmith@example.com. To enable certificate authentication, edit the
imapd-ssl and pop3d-ssl configuration files, and make the following
changes:
* Set TLS_TRUSTCERTS to the filename with your certificate authority's
X.509 certificate.
* Change the TLS_VERIFYPEER setting to "PEER". The setting can also be
changed to "REQUIREPEER" to require all SSL/TLS connections to provide
a certificate. Otherwise, it is optional. If the mail client provides
an SSL certificate, it may be used to authenticate. Without a
certificate, password-based authentication remains an option.
* Change the TLS_EXTERNAL setting to the name of the certificate subject
field that gives the login ID. In the above example, this would be
"TLS_EXTERNAL=emailaddress".
NOTE: GnuTLS's certtool uses "email" as the name of this field. If
Courier-IMAP is compiled with GnuTLS, you should still specify this
field as "emailaddress".
SENDING MAIL VIA AN IMAP CONNECTION
This server allows using the IMAP connection to send E-mail. Normally, the
IMAP protocol provides only access to mail in an existing mail account,
and mail clients must use SMTP in order to send mail. The Courier-IMAP
server has an optional setting to enable mail to be send via an IMAP
connection in a manner that should work with all existing IMAP mail
clients. This can be useful when an account is logged in from a shared
access pool which normally blocks most access to the SMTP port.
This is implemented by enabling a setting in the imapd configuration file
that designates a folder as a special "Outbox" folder. The default setting
is a folder called "Outbox" (IMAP path INBOX.Outbox), but the name can be
changed to anything. This folder, for the most part, is no different than
any other folder. If a folder by that name doesn't exist, it needs to be
created, just like any other IMAP folder. It looks and acts like any other
folder, except that each message added to the folder, via IMAP's APPEND or
COPY command, will also be mailed out by the Courier-IMAP server to the
addresses listed in the To:, Cc:, and Bcc: headers.
It should be possible to use this to send mail from any IMAP client by:
1. Composing a draft message, telling the IMAP client to save the draft
message in its drafts folder on the IMAP server.
2. Opening the drafts folder, and moving or copying the message to the
Outbox folder.
3. The act of copying the message into the Outbox folder will send the
mail. There won't be any explicit notification to the fact that the
message was sent, so it's a good idea to include your own E-mail
address on the Cc: list.
NOTE: it is tempting to configure the IMAP mail client to use Outbox as
its default folder for saving drafts. Resist the temptation. If you
forget, you'll save a partially completed draft, which will be then
obediently mailed out.
NOTE: the message, in addition to being sent, will be saved in the
folder in the normal fashion. After saving the message, reopen the
Outbox folder and delete the sent message, or move it someplace else.
NOTE: when enabled, the Courier-IMAP server will advertize a private
XCOURIEROUTBOX IMAP capability. It is theoretically possible to code an
IMAP mail client that reads this capability and automatically configures
itself accordingly -- when this IMAP capability is present -- to send
E-mail in the normal way but using the IMAP connection. At this time,
I'm not aware of any actual mail clients that know how to do this.
NOTE: many mail clients save some additional internal information in
headers of draft messages. The internal information is normally removed
before the mail client sends the message. Make sure that none of this
extra information is something that should not be mailed out.
REALTIME FOLDER STATUS UPDATES
If Gamin (http://www.gnome.org/~veillard/gamin/) or FAM
(http://oss.sgi.com/projects/fam/) is installed it will be possible to
allow multiple clients to open the same folder, and have all clients to be
simultaneously notified of any changes to the folder contents.
After installing the server see the imapd(8) manual page for more
information.
Account OPTIONS
If the option 'disableimap' or 'disablepop3' is set to a non-zero value,
then logins via IMAP or POP3 respectively will be disabled for that
account. You can use the DEFAULTOPTIONS setting to disable a service
globally and then re-enable it for individual accounts; for example,
setting DEFAULTOPTIONS="disableimap=1" will disable IMAP access for all
accounts except those which have option disableimap=0
See README_authlib.html in the courier-authlib package for information on
how to set per-account options.
SMAP
Starting with Courier-IMAP 2.0, the server supports an experimental mail
access protocol, dubbed "Simple Mail Access Protocol". SMAP is an
experiment to provide enhanced mail processing beyond what's currently
possible with IMAP. SMAP's purpose is to prototype and develop advanced
mail access functionality that's not possible with IMAP. SMAP is disabled
by default. Uncomment the SMAP_CAPABILITY setting in the imapd
configuration file in order to enable SMAP. The Cone mail client supports
SMAP.