courier

このファイルはローカルのエイリアスに対するフィルタリングの際に用いられる アカウントのホームディレクトリを１行で記述します。

フィルタリング機能が有効にされている場合、 ローカル受信者は不必要なメールを拒否するために メールフィルタを設定することができます。 /etc/courier/aliases ファイルにはメールのローカルエイリアスを記述できます。 このようなエイリアスアドレスに対するメールをフィルタリングしたい場合、 フィルタリング指示を指定するために利用するアカウントを決めて、 そのホームディレクトリをこのファイルに記述します。 フィルタリングの引数は"alias-address" のような形になり、 addressはエイリアスアドレスです。 詳しくはlocalmailfilter(7)を参照してください。

技術的な理由から、複数の受信者が定義されたエイリアスアドレスに対する、 内容フィルタによるフィルタリングはできません。

このファイルに対する変更はすぐに反映されます。

このファイルには authdaemond (認証デーモン)の設定を記述します。 authlib(7)を参照してください。

このファイルにはLDAP認証の設定を記述します。 authlib(7)を参照してください。

このファイルにはインストール済みの認証モジュールを１行で記述します。 ここで指定された認証モジュールはローカルメールアドレスを マシンの実アカウントに対応づけたり、 ホームディレクトリやユーザ名やグループ名などを得るために用いられます。

インストール時に選択された認証モジュールは、２種類の方法で使用されます。 個別の認証モジュールは/usr/lib/courier/authlibディレクトリにインストールされ、 POP3やIMAPの接続認証、あるいはESMTPユーザ認証で用いられます。 たいていいくつかの認証モジュールがインストールされています。 たとえば、 authuserdb は仮想アカウントを認証し、 authpam は実システムアカウントを認証します。 POP3、IMAP、ESMTPの各サーバは コマンドラインから認証モジュールのリストを受け取るので、 インストール後でも引数を変更することにより 認証モジュールを無効にしたり再構成したりすることが可能です。

しかし他のサーバについては、主にパフォーマンス上の理由から、 認証モジュールは各プログラムに直接リンクされています。 Courierの主スケジューラーはアカウントのメールボックスの場所を得るために アカウント認証情報を必要をしますが、 メールが配達されるたびに認証用のモジュールを起動することは かなりのオーバヘッドになるため、認証モジュールは直接リンクされています。 CourierのHTTP webmailサーバも直接リンクされた認証用モジュールを使用しています。

そこで、 /etc/courier/authmodulelist ファイルには実際に使用する認証モジュールを、使用する順に記述します。 デフォルトではインストールされたすべての認証モジュールが記述されます。 もしこのファイルがない場合には、インストール済みのすべての認証モジュールが 設定順に用いられます。

このファイルには MySQL 認証の設定を記述します。 authlib(7) を参照してください。

自動返送とフィルタリングが有効化されている場合に、 システムレベルのクォータ値をこのファイルに設定します。 なおこの設定は、当該アカウントが直接ログインできない場合のみ意味があり、 ログインできる場合は簡単にクォータを再設定できてしまいます。

autoresponsesquotaファイルには "Cnnn" か "Snnn" を (あるいはその両方を１行で) 記述します。 Cnnnは最大 #nnn 個の自動返信を作成可能にします。Snnnはすべての自動返信があわせて #nnn バイトになるまで作成可能にします。 CnnnとSnnn両方が記述された場合は、両方の制限が適用されます。 このファイルがなかった場合には自動返信には制限はありません。 この設定はシステム全体に対し有効です。 特定のMaildirに対して別の設定を使いたい場合には、 autoresponsesquotaファイルをそのMaildir内に作成してください (優先されます。)

このファイルには、メールがすぐに配送できない場合に 回送すべきマシン名を１行で記述します。ファイル中の空白はいけません。

メールは warntime ファイルで指定された時間配送できないと、backuprelayに回送されます。 backuprelay が指定された場合、遅配の配送ステータス通知メッセージは作成されません。 元のメッセージが遅配の配送ステータス通知を要求していない場合でも、 メッセージは回送されます。

この機能は大量のメールを扱うメールリレーにおいて、 配送できないメールのために大量にメールキューを用意しておくのを 防ぐためにも用いられます。 なおこの機能はすべての配送不能なメールに対して働くことを留意してください。 メールの宛先がローカルアカウントで、 そのアカウントのフィルタリング指示で一時配送不能エラーとなっている場合でも、 指定の時間が経過すると回送されてしまいます。

現在のところこのバックアップ機能はSMTP経由で動作しますが、 Courierはプロトコルに依存しないメールサーバなので、 将来バックアップ先にSMTP以外のプロトコルも指定できるようになるかもしれません。

複数の回送先を指定するには、 同じマシン名に複数のIPアドレスを割り当ててください。 なおCourierはここで指定されたマシン名の MXフィールドとAフィールドの両方をチェックします。

このファイルは数値のみの１行からなります。 数値は１つのメッセージの最大受信者数を指定します。 Courierは指定の数値より多くの受信者を持つメールを受け取った場合には、 受信者が指定の数値以下になるようにメールをコピーして受信者を分割します。 もし batchsize ファイルが存在しない場合は、最大100受信者になります。

この設定ファイルはドメインベースの不要メールのフィルタリング設定を記述します。 #文字ではじまる行はコメントとして無視されます。 それ以外の行には以下に挙げる指示が適当な順番で指定されます:

このファイルではwebmailサーバのカレンダー機能の基本設定を行います。 カレンダー機能は開発中であり、現在は基本的なサービスのみ提供されています。 このファイルが存在しなければカレンダー機能は無効です。 このファイルが存在する時はその中身は一単語 "local" でなければなりません。

echo "local" >/etc/courier/calendarmode

このファイルは他者読み取り権がなければならないため、umaskを必要以上にきつくしないようにしてください。

このファイルにはCourierの一般的な項目を記述します。 デフォルトの設定がインストールされるので、 詳細についてはそのファイルの内容を参照してください。

このファイルにはメールのドメイン名を1行で記述します。 ドメインなしのメールアドレスに対してここで記述したドメイン名 @defaultdomain が追加されます。 もしdefaultdomainファイルが存在しない場合は、 me ファイルの内容が用いられます。

この defaultdomain ファイルの中身は、 Courierのwebmailサーバから送られたメールの送信者アドレスの、 ドメイン名が指定されていない場合のデフォルトのドメイン名にもなります。 このdefaultdomain ファイルが存在しない場合は、マシンのホスト名が用いられます。

このファイルには、 各ユーザのホームディレクトリで配送指示に用いられるファイル名を1行で記述します。 このファイルが存在しない場合、 $HOME/.courier、 $HOME/.courier-foo、$HOME/.courier-default 等が用いられます。 このファイルの内容が "qmail" の場合、 $HOME/.qmail、$HOME/.qmail-foo、 $HOME/.qmail-default 等になります。

このファイルには配送ステータス通知メッセージの From:ヘッダ行の内容を1行で記述します。 このファイルはヘッダそのものを、"From: "部分を除いて記入します。 dsnfrom ファイルがない場合、デフォルトで次のFrom行が用いられます: "Courier mail server at me" <@>

Maximum size, in bytes, of a message whose contents are included in delivery status notifications. By default, the entire message is only included in non-delivery notices (failures). Only the headers will be returned for delay notifications (warnings) and return receipts; or for failures if the original message is larger than dsnlimit. If missing, dsnlimit is set to 32K.

The sender can request that the entire message be returned even on delayed notices or return receipts, however Courier will ignore this request if the message size exceeds this limit.

This configuration file specifies whether mail filtering is enable. This file, if it exists, contains a single line of text that specifies which kind of mail will be filtered. The possible values are:

If you want to specify more than one source of mail, such as ESMTP and local mail, specify both esmtp and local, separated by a space character.

This file lists all domains that Courier accepts mail for via ESMTP. This file is in the same format as the locals file. If this file is missing, Courier uses the single domain specified in me (or the system machine name).

This is a binary database file that lists additional domains that Courier accepts mail for, just like esmtpacceptmailfor. A binary database file will be faster than a flat text file when the number of domains is large. Courier will accept mail for domains listed in either esmtpacceptmailfor or esmtpacceptmailfor.dat. esmtpacceptmailfor.dat is created by the makeacceptmailfor command. You can use both esmtpacceptmailfor.dat and esmtpacceptmailfor at the same time. Put your most popular domains in esmtpacceptmailfor, and put the rest of them into esmtpacceptmailfor.dat.

This configuration file configures ESMTP authentication for the ESMTP client. This is a text file of zero or more lines that contain the following fields:

relay userid password

When Courier connects to a remote ESMTP relay, Courier will authenticate itself using userid and password. These fields are separated by one or more whitespace characters. Because this file contains passwords, it must not be world or group readable, and owned by the user "daemon".

ESMTP negotiation will take place, and Courier will use a SASL authentication method supported by both Courier and the remote ESMTP server. Currently Courier supports PLAIN, LOGIN and CRAM-MD5 authentication. CRAM-MD5 is preferred over the other two, and PLAIN is preferred over LOGIN.

Courier also supports ESMTP over SSL (the ESMTP STARTTLS extension). If ESMTP STARTTLS is enabled, STARTTLS will be used to establish a secure link first. The authentication will take place afterwards, over a secure channel.

Changes to this file take effect, more or less, immediately (existing connections are not affected, but new connections will read the updated data).

This file is used to initialize the environment and parameters for courieresmtpd. A default file will be provided during installation. See the comments in the file for more information. For changes to this file to take effect you run the esmtpd stop command followed by esmtpd start.

This file contains one line of text that specifies how long courieresmtp waits after a failure to contact the remote mail server before another attempt is made. courieresmtp (not to be confused with courieresmtpd) delivers outgoing mail to remote mail servers. The timeout is specified as an integral number, optionally followed by m - minutes, or h - hours. Otherwise it is specified in seconds.

The courieresmtp process delivers mail that's routed to external mail relays, via ESMTP. When attempting to initally contact a mail server courieresmtp waits for the amount of time specified by esmtptimeoutconnect (see below). esmtptimeoutconnect is usually set to a relatively long period of time, in order to accomodate slow mail servers. A large number of messages queued up for an unreachable mail server can tie up delivery slots that can be put to a better use by reassigning them for mail to another domain. Although Courier does not usually assign all delivery slots for messages to the same domain (this is a tuneable parameter), it is still not very healthy to have a bunch of courieresmtp daemons spinning their wheels, doing nothing.

The situation worsens when there is a large number of mail relays that accept mail for the same domain, and all of them are unreachable due to a network failure. That's because the esmtptimeout waiting period is used for each individual mail relay. Multiply esmtptimeout by the number of servers to see how large the delay really will be.

esmtpdelay is implemented internally in the courieresmtp module. The main Courier scheduling daemon is not aware of what's happening internally in courieresmtp. When courieresmtp fails to contact any mail relay for the domain, the message is postponed, and the esmtpdelay timer is set. Any additional messages received by the same courieresmtp daemon (for the same domain), are immediately postponed without any attempt to contact a remote mail relay. When the amount of time set by esmtpdelay expires, courieresmtp will attempt to make another delivery attempt as usual.

If esmtpdelay does not exist, the default delay is five minutes. Any messages that are postponed look like any other temporary failure to courierd. Delivery attempts are rescheduled as if a real temporary failure took place. Therefore it does not make sense to set esmtpdelay to be greater than retryalpha (see below). When retryalpha is smaller is esmtpdelay, you'll just messages spinning through the mail queue, with useless delivery attempts being attempted because esmtpdelay still hasn't expired.

Occasionally you might observe somewhat strange behavior on systems with heavy mail traffic. esmtpdelay applies separately to each individual instance of courieresmtp. When a remote mail server keeps going up and down, it is possible to end up with multiple courieresmtp daemons handling mail for the same domain, but only some of them will encounter a network failure, purely by the luck of the draw. The remaining daemons will be able to establish a connection. So you'll end up with some courieresmtp daemons being able to deliver mail immediately, while the rest are still waiting patiently for esmtpdelay to expire, postponing all messages in the meantime. Some messages - but not all - will be immediately postponed without a delivery attempt, becauses they ended up getting to a daemon which is waiting for esmtpdelay to expire.

Another anomalous situation may happen when a courieresmtp daemon gets reassigned to another domain, and then receives more mail for the previous domain. This can happen when you have a lot of mail going through. Although Courier tries to shuffle all mail for same domain into one pile, the scheduler still tries to dispatch mail on "first-come, first-serve" basis, as much as possible. When that happens another delivery attempt will be made immediately, because the previous esmtpdelay was cancelled when the daemon got reassigned to another domain.

There can also be occasional abnormalities that affect systems with light traffic. When there is a domain with several mail relays of equal priority, one mail relay is chosen at random for the connection attempt. If some of the equal-priority mail relays are unreachable and a courieresmtp daemon picks it, it will start the esmtpdelay timer and refuse to deliver any more mail until it expires, even if most of the mail servers are functional. This will happen only with mail relays of the lowest priority. Otherwise, courieresmtp will always try to contact another mail relay of a still lower priority, before giving up and setting the esmtpdelay timer. Another courieresmtp daemon will not be started for the same domain if there's already an existing one, so all delivery attempts will be turned away until esmtpdelay expires. Another courieresmtp daemon will be started only in the event of multiple simultaneous delivery attempts that happen to coincide at the same time.

This is somewhat mitigated by the fact that all courieresmtp daemons are killed after a short period of total inactivity (currently one minute), so that longer intervals specified by esmtpdelay are ignored. Note, however, that receiving a message to deliver, and then postponing it immediately, does count as some activity.

esmtpdelay can be turned off by setting it to 0 seconds. esmtpdelay is designed for servers that handle heavy amount of mail that wish to avoid having outbound delivery slots tied up due to network failures, at an expense of an occasional anomalous behavior due to harmless paranoia. esmtpdelay may prove to actually make things worse for systems that carry only light mail traffic, if they are burdened with a task of exchanging mail primarily with external systems that are not properly maintained.

The complete greeting banner displayed by courieresmtpd. Changes to this file take effect immediately.

This file contains one line of text, what Courier calls itself in the EHLO or HELO command sent to a remote SMTP server. me is used if this file does not exist.

This file is used by the ESMTP module, and it contains one or more lines in the following form:

domain:relay[,port][/SECURITY=STARTTLS][/SECURITY=NONE]

domain is any SMTP domain. relay specifies a fixed mail relay for this domain. relay is optionally followed by a comma and a port number, to specify a port other than the default port 25. If an address's domain is not found in esmtproutes, Courier looks for MX and A records as usual (and always delivers to port 25). If the domain is found in esmtproutes, however, any MX or A records for the domain are ignored; instead Courier delivers the message to the specified relay.

relay can be another domain, or an explicit IP address inside brackets. For example, if esmtproutes contains the following:

example.com: relay.domain.com
domain.com: [192.68.0.2]

Mail for example.com is delivered to relay.domain.com, ignoring any MX records for example.com. Mail for domain.com will be delivered to the machine at IP address 192.68.0.2. All other domains will have their MX and A records looked up.

esmtproutes may contain comments, any line that starts with the # character is ignored. Also, wildcards are allowed:

.example.com: [192.68.0.3],26

This specifies that any address of the form <anything@anything.example.com> will be delivered to the mail server at this IP address, but on port 26.

esmtproutes is read from top to bottom, stopping as soon as a first match is found.

domain may be empty, this specifies a smarthost for all domains. For example, if esmtproutes contains the following text:

example.com: relay.example.com
        :[192.68.0.4]

This specifies that all mail to example.com is rerouted to relay.example.com. All other mail is routed to the IP address 192.68.0.4.

If relay is empty, Courier interprets it as an explicit directive to use MX and A records from DNS. For example:

example.com:
:[192.68.0.4]

This uses MX and A records for all messages to example.com. All other mail is rerouted to the IP address 192.68.0.4.

The optional /SECURITY=STARTTLS flag indicates that mail to this domain should be automatically upgraded to use the SECURITY ESMTP extension. See the Courier installation notes for a description of SECURITY, what it does, and how to configure it.

The /SECURITY=NONE flag prevents Courier from using the STARTTLS ESMTP extension even if the remote server claims to support it. Use this flag to deliver mail to misconfigured Microsoft Exchange relays that claim to support STARTTLS, but always report a failure to a STARTTLS request.

Changes to this file take effect immediately, more or less. Existing courieresmtp processes that already have an established connection will ignore any changes.

This file contains one line of text that specifies the timeout for an SMTP command. The timeout is specified as an integral number, optionally followed by m - minutes, or h - hours. Otherwise it is specified in seconds. This timeout is used for all SMTP commands, unless the SMTP command has a dedicated timeout defined by a different configuration file. The default timeout is ten minutes.

This file contains one line of text that specifies the timeout for an SMTP connection attempt. Most TCP/IP stacks wait an extraordinary long period of time for SMTP connections to go through. This configuration setting limits the amount of time Courier waits for the SMTP connection to complete. The default timeout is one minute. Set esmtptimeoutconnect to 0 in order to use whatever default timeout your TCP/IP stack uses.

This file contains one line of text that specifies the timeout for transferring the message contents or individual replies. The default timeout is five minutes. You WILL HAVE TO bump this up if you're on a slow link, and you want to send large messages. A 28.8Kbps link can be optimistically expected to push 3,000 bytes per second. With a five minute cutoff, you will not be able to send or receive anything larger than about 870 Kb. You have no business sending or receiving 870 Kb messagesl, if all you have is an analog 28.8Kbps connection.

This file contains one line of text that specifies the timeout for the initial EHLO or HELO command. Courier will wait this amount of time to receive the initial greeting banner from the remote SMTP server, and a response to the subsequent EHLO/HELO command. The default value is 5 minutes.

This file contains one line of text that specifies how often outbound SMTP sessions are kept idle after delivering a message. After Courier connects to an SMTP server and completes the attempt to deliver the message, the SMTP session is kept idle for this time interval before being shut down. If Courier receives another message for the same domain, it will be delivered using the existing SMTP session, instead of establishing a new one. Note that some SMTP servers have a very short idle timeout, Qmail's is only two minutes. The default value is 60 seconds.

Note that there's also a separate limit to the maximum number of simultaneous SMTP sessions to the same domain. That limit is currently four, which is adequate for nearly every situation, so for now it will be set by an undocumented configuration file.

This file contains one line of text that specifies how often Courier will issue a useless RSET command when the connection is idle (see esmtptimeoutkeepalive). While waiting for any more messages to deliver to the same domain, or for the esmtptimeoutkeepalive interval to expire, courieresmtp will transmit RSET commands at regular intervals specified by this configuration file. The default value is 0 seconds, which turns off the keepalive ping altogether. This configuration settings must be for a shorter time interval than esmtptimeoutkeepalive for it to make any sense. Note that other system administrators may consider this to be a very rude thing to do. Also keep in mind that this may generate quite a bit of idle traffic. If you have Courier configured for a maximum number of 200 outbound SMTP sessions and a 30 second esmtptimeoutkeepaliveping setting, then you can have as much as an average of around seven pings every second!

This file contains one line of text that specifies how long Courier waits for the external SMTP server to acknowledge the QUIT command, before Courier unilaterally tears down the connection. The default value is 10 seconds. This must be a small value because Courier needs to be able to shut down quickly, on very short notice.

If this file exists, its contents will be automatically appended to all messages sent by the webmail server.

This file lists locally-hosted domains. It is very similar in function to the locals control file. Any address with a domain listed in hosteddomains is considered to be a local address. The difference between hosteddomains and locals is that domains listed in hosteddomains are not removed from individual addresses before looking up the location of their mailboxes. For example, if the domain "example.com" appears in locals, the address user@example.com will have example.com removed, and then Courier will look for a local mailbox named "user".

If the domain "example.com" appears in hosteddomains instead, Courier will look for a local mailbox named "user@example.com" instead.

The contents of the hosteddomains configuration file is a list of domains, one per line, in lowercase. You must run the makehosteddomains command for any changes to take effect.

This file is used by the webmail server. It contain a default systemwide list of accessible LDAP address books. A default file will be installed, listing some common Internet address books. Each line in this file contains the following information:

name<tab>host<tab>port<tab>suffix<tab>binddn<tab>bindpw

"<tab>" is the ASCII tab character.

This file is used by the courierldapaliasd process. See courierldapaliasd(8) for more information.

If this file exists, Courier will not distinguish being lowercase and uppercase local accounts, so that john@example.com and John@example.com will refer to the same local mailbox (where example.com is your domain). Postmaster, postmaster, and POSTMASTER always refer to the same account, even if locallowercase does not exist.

This file contains one or more lines of text, where each line contains a valid mail domain. Any E-mail address without @domain, or with a domain that can be found in locals will be considered to be an address of a local mailbox. A domain can be specified with a leading dot:

.domain.com

This is called a "wildcard". Any domain ending in domain.com, such as a.domain.com, b.domain.com, a.b.c.domain.com - but NOT somedomain.com - will be considered local. Note that domain.com is NOT included in this wildcard. Both "domain.com" and ".domain.com" should be listed.

Specific hosts can be excluded from the wildcard. Example:

!host.domain.com
.domain.com

anything.domain.com is considered to be a local domain, except for host.domain.com. Note that "!host.domain.com" must appear in locals before the .domain.com wildcard.

The "!hostname" syntax is also valid in the esmtpacceptmailfor control file.

If locals does not exist, Courier uses the contents of the me control file (note that me specifies only one domain, second and subsequent lines are ignored). Also, see hosteddomains.

If this file exists then the webmail login screen will have a drop-down list whose contents will be read from this file. This file should contain a list of E-mail domains, one per line. It should be created if Courier's webmail server is used to provide mail access for more than one domain. Instead of typing "user@domain" to log in, it will only be necessary to enter "user", and select the domain from the drop-down list. If this file does not exist it will be necessary to enter the full E-mail address into the webmail login screen.

This file, if exists, sets the global defaults for mail filtering in the webmail server. Mail filtering in the webmail server is a subject worthy of special mention. A full description of how to install and configure webmail-based mail filtering is included in the installation notes for Courier. Refer to the installlation instructions for additional information.

This file, if exists, specifies the location of shared maildirs for the webmail and IMAP server. Normally, each mailbox must be separately configured to access every shared maildir, by the maildirmake(1) command. This file allows shared maildirs to be set globally for everyone. Everyone's webmail and IMAP server will pick up the shared maildirs specified in this file. See maildirmake(1) for more information.

This file contains one line whose contents is a pathname to the maildrop(1) mail delivery agent. If Courier knows that the delivery agent used to delivery mail locally is maildrop(1) then certain delivery optimizations are possible. This configuration file does NOT actually specify that maildrop(1) should be used as a local mail delivery agent, it only specifies where maildrop(1) is installed. The default local mail delivery instructions are specified in the courierd configuration file. If the specified delivery instruction specify running an external program whose pathname matches the one specified by this configuration file, Courier assumes that it's maildrop(1), and will use maildrop-specific options to optimize mail delivery.

This configuration file is initialized, by default, to point to the version of maildrop(1) that's integrated with Courier. The integrated version of maildrop(1) is configured slightly differently than the standalone version of maildrop(1).

Although you can set the maildrop configuration file to point to some other version of the maildrop mail filter, you MUST set the maildropfilter configuration file (see below), to point to the integrated version of maildrop.

This file contains one line whose contents is a pathname to the maildrop(1) mail delivery filter. In addition to being a delivery agent, maildrop can also be used as a mail filtering engine. If this file exists, Courier will be capable of invoking recipient-specified mail filters when a message is received. If the mail filtering rules reject the message, Courier will not accept the message for delivery. This means that when receiving mail via ESMTP, Courier will reject the ESMTP transaction without even accepting the message from the remote mail server.

This file is not installed by default. To activate mail filtering for local recipients, simply copy the contents of the maildrop configuration file to maildropfilter.

This file contains systemwide mail filtering instructions for maildrop(1) deliveries. This configuration file is optional, and is used by maildrop(1) when it is invoked as a traditional post-delivery mail filter. See maildropfilter(6) for more information.

This file contains one line whose contents is a valid machine name. When a single installation of Courier is shared over a network, each machine that's running Courier must have a unique me file. If me is missing, Courier uses the result of the gethostname() system call.

If a message does not have a Message-ID: header, Courier may decide to create one. The host portion of the new header will be set to the contents of msgidhost, which contains one line of text. If msgidhost does not exist, me will be used in its place. Changes to this file take effect immediately.

Courier's webmail server lets the contents of the From: header be set for mailed messages. If this configuration file exists, the ability to set the contents of the From: header is disabled.

This file specifies how long Courier normally tries to repeatedly deliver a message, before giving up and returning it as undeliverable. Messages are immediately returned as undeliverable when a permanent failure is encountered (such as the recipient address not being valid). Attempts to deliver the message when there's a temporary, transient, error (such as the network being down) will be repeatedly made for the duration of time specified by this configuration file. This file contains a number followed by the letter 'w' for weeks, or 'd' for days. It is also possible to use 'h' for hours, 'm' for minutes, or 's' for seconds. Only integers are allowed, fractions are prohibited. However, you can use '1w2d' to specify one week and two days. If queuetime is missing, Courier makes repeated delivery attempts for one week.

These control files specify the schedule with which Courier tries to deliver each message that has a temporary, transient, delivery failure. retryalpha and retrygamma contain a time interval, specified in the same way as queuetime. retrybeta and retrymaxdelta contain small integral numbers only.

Courier will first make retrybeta delivery attempts, waiting for the time interval specified by retryalpha between each attempt. Then, Courier waits for the amount of time specified by retrygamma, then Courier will make another retrybeta delivery attempts, retryalpha amount of time apart. If still undeliverable, Courier waits retrygamma*2 amount of time before another retrybeta delivery attempts, with retryalpha amount of time apart. The next delay will be retrygamma*4 amount of time long, the next one retrygamma*8, and so on. retrymaxdelta sets the upper limit on the exponential backoff. Eventually Courier will keep waiting retrygamma*(2^retrymaxdelta) amount of time before making retrybeta delivery attempts retryalpha amount of time apart, until the queuetime interval expires.

The default values are:

This results in Courier delivering each message according to the following schedule, in minutes: 5, 5, 5, 15, 5, 5, 30, 5, 5, 60, 5, 5, then repeating 120, 5, 5, until the message expires.

Maximum size of the message, in bytes, that Courier accepts for delivery. Courier rejects larger messages. If sizelimit is set to zero, Courier accepts as large message as available disk space permits. If the environment variable SIZELIMIT is set at the time a new message is received, it takes precedence and Courier uses the contents of the environment variable instead. Changes to this file take effect immediately. The SIZELIMIT environment variable is for use by individual mail submission agents. For example, it can be set by the smtpaccess configuration file (see makesmtpaccess(8) for more information) for mail from certain IP addresses.

If sizelimit does not exist, and SIZELIMIT is not set, the maximum message size defaults to 10485760 bytes.

submitdelay specifies the delay before the first delivery attempt for a message that has been entered into the mail queue. Normally, the first delivery attempt is made as soon as possible. This setting delays the initial delivery attempt. It is normally used when you have a mail filter installed that detects duplicate messages arriving in a short period of time. If the mail filter detects this situation it can use the cancelmsg(1) command to reject duplicate messages in the queue (and return them back to the envelope sender).

submitdelay specifies a time interval in the same format as queuetime.

If this configuration file exists, Courier's webmail server will set the X-Sender: header on all outgoing messages. This is a good idea if the webmail server allows the user to set the contents of the From: header. Note that Courier records the system userid of the sender in all locally-sent messages (which includes messages mailed by the webmail server), which is sufficient in most cases. In cases where you have many virtual accounts that share the same system userid, this configuration file provides a way to positively identify the sender of the outgoing message.

uucpme sets the UUCP nodename of the Courier mail relay. See courieruucp(8) for more information.

uucpneighbors is used by the courieruucp module to specify Courier's configuration for relaying mail via UUCP. See courieruucp(8) for more information.

If this file exists, headers of messages sent to/from UUCP addresses will be rewritten. Normally, only the message envelope sender and recipients are rewritten, the existence of this file causes the headers to be rewritten as well.

warntime specifies an amount of time in the same format as queuetime. If a message still has not been delivered after this period of time, Courier sends a warning message (a "delayed" Delivery Status Notification) to the sender. If warntime is missing, Courier sets warntime to four hours.