Anyone can use couriermlm, not just the system administrator. The Courier mail server translates an address list-name@domain as a local address with a corresponding dot-courier(5) file. Anyone that can install a dot-courier(5) file, and can schedule cron(8) jobs, can run a couriermlm mailing list.

Note that the system administrator can optionally remove the dot-courier(5) support from the Courier mail server. couriermlm will not work in that case.

Setting up a mailing list consists of the following steps:

Run couriermlm create

Use this command to create a directory where couriermlm keps all mailing list related files.

Configure the mailing list

The couriermlm create command initializes the mailing list subdirectory with some default template responses. It is necessary to customize them for your mailing list, and it may be necessary to issue some additional commands in order to configure appropriate mailing list options -- such as enabling unrestricted posting privileges, and enabling moderation.

Create dot-courier(5) files

Set up to run couriermlm to distribute mailing list messages, and process requests.

Set up cron(8)

You need to set up cron(8) jobs to run the couriermlm hourly and couriermlm daily commands, which perform regular mailing list maintenance.

Back up subscription lists

As part of your daily job you should also run the export command, in order to back up the mailing list subscriber information. In the event that the mailing list database gets corrupted or lost, you can restore it from this backup file. See the export command for more information. Note: Setting up a digest for the mailing list requires additional steps. See "Setting up a mailing list digest" below for more information.

The first step is to run the following command:

couriermlm create directory ADDRESS=list@domain

directory is the mailing list directory that will be managed by couriermlm. This directory should not be created in advance, this command creates this directory, and initializes it.

list@domain is the mailing list's address, the address that sends messages to the mailing list.

The directory created by couriermlm create is initialized to contain a number of text files that couriermlm sends back as replies to administrative commands. It is necessary to edit these template files and adjust the text in those files for this mailing list. All template filenames end with .tmpl, and their contents are self explanatory. Some important template files are:

help.tmpl

This text is returned in response to the help command. This text must be modified depending upon whether this mailing list is a moderated mailing list, has a digest version, or if any other non-default configuration options are set for the mailing list.

sub.tmpl

This is the reply that's sent back in response to a subscription request. Less important is unsub.tmpl, which is the response to a request to unsubscribe.

sub2.tmpl

This is the successful subscription confirmation. A brief overview of the mailing list might be appropriate here.

There are some additional configuration files that can be modified to suit your taste:

headeradd

This file can be initialized to contain any mail headers that will be automatically added to every mailing list message. The contents of this file are simply prepended to every message that goes out. Blank lines are not allowed.

headerdel

This file lists any headers that will be automatically removed from every mailing list message before it's sent. List each header one per line, including the : character. For example, to remove all Received: and Date: headers from every message, initialize this file to contain the following two lines:

Received:
Date:

Both the headeradd and headerdel files can be used to implement a popular feature of setting the replies to every message to go to the mailing list. Having "Reply-To:" in headerdel, removes any existing Reply-To: header, and then having "Reply-To: list@domain" in headeradd appends a fixed Reply-To: header to every message.

The create command also creates the following subdirectories in the mailing list directory:

sublist

This subdirectory has the database files that contain the mailing list's subscribtion list.

unsublist

This subdirectory stores files that contain information about addresses that have been unsubscribed from the mailing list. This information might be of some use when tracking down an old subscription. The contents of this directory are not automatically purged, you must set up your own purging mechanism for this directory.

commands, commands.dat

These directories store temporary files that contain pending (unconfirmed) commands for the mailing list manager. The couriermlm commands hourly and daily must be executed regularly in order to periodically purge stale entries.

modqueue

Messages awaiting moderator approval (for moderated lists).

archive

Messages received by this mailing list will be stored here, in addition to being forwarded to subscribers. couriermlm does not automatically do any purging on this subdirectory, you must set up your own archiving mechanism that cleans out this subdirectory.

The last step involves installing a couple of dot-courier(5) files that run couriermlm to receive mailing list messages and administrative commands. The mailing list address, list@domain, corresponds to some dot-courier(5) file. For example, if your system account is john, and your mail domain is example.com, then the dot-courier(5) file for the mailing list <john-list@example.com> is $HOME/.courier-list.

Let's say that the dot-courier(5) file is $HOME/.courier-list. To properly support the mailing list, the following dot-courier(5) files will have to be initialized as follows:

$HOME/.courier-list

This file should be initialized to contain the following delivery instruction:

| /usr/bin/couriermlm msg directory

directory is the created mailing list directory.

$HOME/.courier-list-owner

This file should contain the appropriate delivery instructions for forwarding all mail addressed to <list-owner@domain> to the address of the owner of the mailing list. This can be another E-mail address, or a mailbox specification.

$HOME/.courier-list-default

This file should be initialized to contain the following delivery instruction:

| /usr/bin/couriermlm ctlmsg directory

directory is the created mailing list directory. This dot-courier(5) file provides support for all other addresses of the form <list-command@domain>, where command is a mailing list administrative command. Commands are sent to this mailing list manager by sending a message to one of several special addresses, described more fully in "Mailing list commands", below.

couriermlm may also be run manually from the command line as follows:

/usr/bin/couriermlm command directory [ options... ]

command is a command from the following list. directory is the mailing list directory. The commands are:

create

Create a mailing list.

set

Set mailing list options.

sub

Manually subscribe an address to the mailing list.

unsub

Manually unsubscribe an address from the mailing list.

lsub

List all the subscribers to this mailing list.

laliases

List write-only aliases for this mailing list.

export

Export mailing list subscriber information.

import

Import mailing list subscriber information.

ctlmsg

Receive and interpret a control message.

info

Display a subscription record.

msg

Post a message to the mailing list.

hourly

Perform hourly maintenance. It is necessary to set up a cron(8) job to execute the hourly command once an hour.

daily

Perform daily maintenance. It is necessary to set up a cron(8) job to execute the daily command once a day.

digest

Create a digest. See "Setting up a mailing list digest" below for more information.

The sub, unsub, lsub, laliases, export, and import commands allow manual subscription list management. Normally, subscription-related commands are done by sending an appropriate mailing list command, see "Mailing List Commands", below.

couriermlm sub directory user@domain

This command adds the address <user@domain> to the subscription list. couriermlm will now read a free-form comment or a note from standard input, terminated by an end-of-file (usually CTRL-D). The free-form comment is stored in the subscription database, together with the address, and is shown by the "info" command.

couriermlm unsub directory user@domain

This command remove the address <user@domain> from the subscription rolls. couriermlm will also read a free-form comment, which is added to the subscription record. After removing this address from the subscription rolls, its subscription record is archived in the directory/unsublist directory.

couriermlm lsub directory

This command lists all the addresses subscribed to the list, on standard output, one per line.

couriermlm laliases directory

This command lists all write-only aliases that have been subscribed to the list, together with the subscriber address that added each alias. See "Write-Only Aliases" for more information.

couriermlm export directory

The export command lists the contents of the subscription database on standard output. The export command produces the following output format:

address
subscription information
 ...
address
subscription information
 ...

"address", is an address subscribed to the mailing list. This is followed by its corresponding subscription information, usually a copy of the subscription request that was used to add the address to the mailing list. The subscription information is terminated by a line containing a single period. Any lines in the subscription information that begin with a period have an extra period prepended to them.

couriermlm import directory

The import command reads on standard input a previously exported mailing list subscription database, and adds those addresses to the indicated mailing list.

It is highly recommended to make a regular backup of subscriber information using the export command, in the event that the subscription database gets corrupted. In which case the import command can be used to rebuild the subscription database, in absence of any direct backups of the database files.

The set command sets various list options:

couriermlm set directory option=value option=value...

One or more options can be set with the same command. The available options are:

ADDRESS=address

The base E-mail address for this mailing list.

DIGEST=directory

Enable digests. directory is the pathname to the previously-createddigest list directory. See "Setting up a mailing list digest" below for more information.

KEYWORD=keyword

Set the subject line keyword for mailing list messages. If set, couriermlm inserts "[keyword]" into the subject of every mailing list message, to aid sorting by the recipients.

MAXBOUNCES=n

Maximum number of bounce notifications sent by the hourly command, in order to prevent the mail system from being overloaded. The default is 20 bounce notifications. Any unsent notifications will be carried over to the next hourly job.

MAXMODNOTICES=n

Maximum number of moderation reminders sent by the hourly command, in order to prevent the mail system from being overloaded. The default is 20 moderation reminders. Any unsent reminders will be carried over to the next hourly job.

MAXFETCHSIZE=K

Maximum size, in kilobytes, of a response to the fetch command. The default is 100Kb. This option is used to minimize the impact of abusive requests for the entire archive, with a forged return address.

NAME=name

The name that's listed on the return address of administrative messages. Note that if name contains spaces, you should quote this argument in the shell. The default value is "Courier Mailing List Manager".

NOBOZOS=flag

If flag is "0" couriermlm will not attempt to block misdirected subscribes and unsubscribes that are sent to the mailing list's posting address. If flag is "1" (the default), those kinds of messages will be bounced appropriately.

POST=option

Set posting options. option is one of three values: "subscribers" - only subscribers may post messages to this mailing list (this is the default); "all" - anyone can post messages to this mailing list; "mod" - only subscribers may post, and messages are sent to the list owner for approval (moderation).

POSTARCHIVE=option

Set access to archived messages. option is either: "all" - Anyone can access the mailing list archive; or "subscribers" - only subscribers can access the archive. The default is "all".

PURGEARCHIVE=d

Purge archived mailing list messages after d days. The default is 0 days - messages are never removed from the archive subdirectory.

PURGEBOUNCE=d

Wait d days for the probe message, that automatically unsubscribes undeliverable addresses, to bounce (default: 14 days). Probe messages are sent three days (default) after the first message to an address bounces.

PURGECMD=h

Purge unconfirmed subscribe/unsubscribe requests after h hours (default: 48 hours).

REMODERATE=h

Resend a moderation reminder after h hours (default: 12 hours).

REPORTADDR=address

Mail daily reports of new and removed subscribers to this address. Must be set in order to receive reports. Provide an empty address to stop reporting.

SIMPLECONFIRM=n

If n is 1, confirmation requests may be acknowledged without adding ``yes'' to the subject line. Note: The text in sub.tmpl, unsub.tmpl, and help.tmpl may need adjusting.

SUBSCRIBE=option

Set subscription options. option is either "all", meaning that anyone can subscribe, or "mod", meaning moderated subscription requests, where all subscription requests are sent to the mailing list owner for approval. The default is "all".

STARTPROBE=n

Send a probe to a bouncing address n days after receiving the first bounce. Basically this means that an address must bounce for at least n days before it gets a probe message. The default is 3 days.

Option names and settings are case sensitive. Note: If you set up a digest list, you MUST set identical POSTARCHIVE option for both the main list and the digest list.

The info command displays the subscription record for the requested address:

couriermlm info directory user@domain

This displays the subscription record for "user@domain", which typically consists of a copy of the initial subscription request, and confirmation.

The msg commands reads an E-mail message on standard input, and mails the contents of the message to the mailing list's subscribers.

If the POST option is set to "subscribers", the message is rejected unless the address in its From: header is a subscriber to this mailing list.

Control files headeradd and headerdel are read, and are applied to the message, as described previously.

Mailing list commands can be sent via E-mail to couriermlm by sending a message to <list-command@domain>. The "default" dot-courier(5) file runs couriermlm to receive mail for all addresses of this form.

couriermlm reads the DEFAULT environment variable, which is set by Courier, that indicates the specific command. The available commands are:

help

A simple autoresponder. couriermlm mails the sender the contents of the help.tmpl file.

subscribe

A request to subscribe to this mailing list. couriermlm reads the sender's address in order to determine what address to subscribe.

subscribe-name=domain

Axplicitly specify the address to subscribe to the mailing list, instead of using a return address. In the previous example, sending a message addressed to <my-widgets-subscribe-john=domain.com@example.com> would result in a subscription request for <john=domain.com>. Any unusual punctuation characters in the address must be replaced by a plus sign, followed by two hexadecimal digits that represent the punctuation character's ASCII code.

unsubscribe

A request to unsubscribe to this mailing list.

unsubscribe-name=domain

Explicitly specify the address to unsubscribe from the mailing list.

alias-subscribe

Set up a write-only alias (see below).

alias-subscribe-name=domain

Explicitly specify the subscriber address for which a write-only alias needs to be set up.

There are other commands that are used internally for maintaining the mailing list.

Write-only E-mail aliases can send messages to the mailing list, but they do not receive any mailing list messages themselves. A write-only alias can be set up by any subscriber. Only one write-only alias is allowed per subscribed E-mail address. Write-only aliases are not needed for mailing list that has the POST=all option set.

To set up a write-only alias, the subscriber sends a couriermlm alias-subscribe command. The subscriber's E-mail address can be explicitly specified in a similar manner as the subscribe command.

The subject line of the E-mail message must contain the E-mail write-only alias to be set up, and nothing else. couriermlm responds with a confirmation request, just like when subscribing to the list. This request must be acknowledged in the same way.

A subscriber's write-only alias can be changed at any time by repeating this procedure. The new alias replaces the previous one. To prevent abuse, there's a limit of at most one alias-subscribe command every 30 minutes.

Leave the subject of the E-mail message blank in order to remove an existing write-only alias,

couriermlm supports mailing list digests. Mailing list digests are created as a second, separate, mailing list. The create command initializes a second mailing list directory, and then additional configuration takes place which ties links the main mailing list toe the digest list.

If the mailing list address is list-address@example.com, the address of the digest version of the mailing list is usually list-address-digest@example.com, but it doesn't have to be this address. The only requirement is that the directory for the digest version of the mailing list must reside on the same filesystem as the directory for the mailing list itself, and both must be owned by the same userid.

To set up a mailing list digest, first proceed with the steps to create the mailing list itself. After the mailing list is created and configured, proceed as follows:

Create the digest list directory

Execute the create command to create the digest version of the list:

/usr/bin/couriermlm create \
   /path/to/digest/list/directory \
   ADDRESS=list-address-digest@example.com

Use the full pathname to the mailing list directory, and the address of the digest version of the mailing list.

Configure the digest list

Execute the set command to set any appropriate options for the digest list. There one important differences to note: messages are not posted to the digest list directly, so there is no moderation option, however the digest version of the list can have moderated subscription requests.

Link the two lists

Set the DIGEST option for the main mailing list, specifying the directory of the digest list. This keyword lets couriermlm know that a digest version is available. Note: You MUST set identical POSTARCHIVE option for both the main list, and the digest list.

Create dot-courier(5) files

It is necessary to create dot-courier(5) files for the digest list just like the main list, except for some important differences, which are noted below.

Create cron(8) jobs

It is also necessary to create cron jobs for the digest list exactly like the main list, to run the hourly and daily cleanup. It's possible to set up one set of cron jobs to run hourly and daily cleanups consecutively for both lists.

Create a digest cron(8) job

The digest creates and distributes the digest version of the list. It can be executed by a cron(8) job, or the command can be executed manually.

The main mailing list is supported by three dot-courier(5) files, as previously described: the posting address, the owner forwarding address, and the default address that handles administrative control messages. In the following example, the names $HOME/.courier-list, $HOME/.courier-list-owner, and $HOME/.courier-list-default are used to represent each one of these files, and the following names are used to represent the dot-courier(5) files that correspond to the digest version of the mailing list: $HOME/.courier-list-digest, $HOME/.courier-list-digest-owner, and $HOME/.courier-list-digest-default. Note, however, that the digest version of the mailing list can have any name, not necessary the name of the list, followed by "digest".

The contents of both $HOME/.courier-list $HOME/.courier-list-digest must be the same. Sending a message to the digest address should really end up sending a message to the main mailing list. Do not put the address of the digest mailing list directory in $HOME/.courier-list-digest, instead specify the address of the main mailing list directory. Just copy $HOME/.courier-list to $HOME/.courier-list-digest.

However, the contents of $HOME/.courier-list-digest-default must specify the directory of the digest version of the mailing list. The digest list is managed separately from the main list, it has its own subscriber list that is separate from the list of subscribers to the main list. $HOME/.courier-list-default can simply be copied to $HOME/.courier-list-digest-default, then the directory can be changed in the latter.

$HOME/.courier-list-owner may use the same mailing list owner address as $HOME/.courier-list-digest-owner, or it can specify a different address. The both the digest and the main mailing list can have the same mailing list owner/moderator, or have a different owner/moderator.

The following command must be executed in order to link the two lists together:

/usr/bin/couriermlm set \
    /path/to/main/list/directory \
    DIGEST=/path/to/digest/list/directory

Setting the DIGEST option on the main list lets couriermlm know that a digest version is available. The DIGEST option must either use an absolute pathname, or a pathname that's relative to the main list directory (NOT the current directory).

When the DIGEST option is set, messages are simultaneously distributed to the mailing list's subscribers, saved in the archive subdirectory of the main list, then placed in the modqueue subdirectory of the digest list. Digest list do not employ moderation -- any moderation must take place on the main list -- so the modqueue subdirectory is recycled to compile individual messages for the digest.

Finally, something needs to be done in order to actually distribute the digest to the digest list's subscribers. This is done by running the following command:

/usr/bin/couriermlm digest /path/to/digest/directory N H

This command creates a digest, and sends it out. The N and H arguments are optional. The digest is created only if there's at least N messages that are waiting to be sent in the digest list, or if the oldest message is at least H hours old. Both options default to 0, so the default behavior is to send a digest with all unsent messages.

Note that when the digest is created, ALL unsent messages are packaged into the digest, even if some messages are more recent than the time interval specified by the H option. A cron(8) job can be set up to run the digest command, or run it manually.

couriermlm automatically provides the From:, To: headers on a message digest. Additional headers may be specified by the headeradd file in the digest list directory. The headerdel file has no effect. Note that the individual messages in the digest are copies of the messages from the main mailing list, and thus have the headeradd and headerdel headers processed from the main mailing list directory.