安装和配置Postfix和Dovecot

这是我们的设置和配置邮件服务器系列的第二篇文章。在这篇文章中，我们将向您展示如何安装和配置Postfix和Dovecot，这是我们邮件系统的两个主要组件。

Postfix是一种开源邮件传输代理（MTA），一种用于发送和接收电子邮件的服务。 Dovecot是IMAP / POP3服务器，在我们的设置中，它还将处理本地传递和用户身份验证。

本教程是为Ubuntu 16.04编写的，但是，只需稍加修改即可进行相同的步骤，适用于所有较新的 Ubuntu 版本。

先决条件

在继续学习本教程之前，请确保您以个具有sudo特权的用户身份登录。

安装Postfix和Dovecot

Ubuntu默认存储库中的Dovecot软件包已过时。为了利用imap_sieve模块，我们将从Dovecot社区存储库中安装Dovecot。

使用以下 wget命令将存储库GPG密钥添加到apt源密钥环：

wget -O- https://repo.dovecot.org/DOVECOT-REPO-GPG | sudo apt-key add -

使用以下命令启用Dovecot社区存储库：

echo "deb https://repo.dovecot.org/ce-2.3-latest/ubuntu/$(lsb_release -cs) $(lsb_release -cs) main" | sudo tee -a /etc/apt/sources.list.d/dovecot.list

sudo apt update
sudo debconf-set-selections <<< "postfix postfix/mailname string $(hostname -f)"
sudo debconf-set-selections <<< "postfix postfix/main_mailer_type string 'Internet Site'"
sudo apt install postfix postfix-mysql dovecot-imapd dovecot-lmtpd dovecot-pop3d dovecot-mysql

后缀配置

我们将设置Postfix以使用虚拟邮箱和域。

首先创建sql配置文件，该文件将指示postfix如何访问 MySQL数据库，该数据库在本系列的第一部分中创建。

sudo mkdir -p /etc/postfix/sql

打开您的文本编辑器并创建以下文件：

/etc/postfix/sql/mysql_virtual_domains_maps.cf

user = postfixadmin
password = P4ssvv0rD
hosts = 127.0.0.1
dbname = postfixadmin
query = SELECT domain FROM domain WHERE domain='%s' AND active = '1'

/etc/postfix/sql/mysql_virtual_alias_maps.cf

user = postfixadmin
password = P4ssvv0rD
hosts = 127.0.0.1
dbname = postfixadmin
query = SELECT goto FROM alias WHERE address='%s' AND active = '1'

/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf

user = postfixadmin
password = P4ssvv0rD
hosts = 127.0.0.1
dbname = postfixadmin
query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('%u', '@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf

user = postfixadmin
password = P4ssvv0rD
hosts = 127.0.0.1
dbname = postfixadmin
query  = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

/etc/postfix/sql/mysql_virtual_mailbox_maps.cf

user = postfixadmin
password = P4ssvv0rD
hosts = 127.0.0.1
dbname = postfixadmin
query = SELECT maildir FROM mailbox WHERE username='%s' AND active = '1'

/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf

user = postfixadmin
password = P4ssvv0rD
hosts = 127.0.0.1
dbname = postfixadmin
query = SELECT maildir FROM mailbox,alias_domain WHERE alias_domain.alias_domain = '%d' and mailbox.username = CONCAT('%u', '@', alias_domain.target_domain) AND mailbox.active = 1 AND alias_domain.active='1'

创建SQL配置文件后，更新主后缀配置文件，以包含有关存储在 MySQL数据库中的虚拟域，用户和别名的信息。

sudo postconf -e "virtual_mailbox_domains = mysql:/etc/postfix/sql/mysql_virtual_domains_maps.cf"
sudo postconf -e "virtual_alias_maps = mysql:/etc/postfix/sql/mysql_virtual_alias_maps.cf, mysql:/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf, mysql:/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf"
sudo postconf -e "virtual_mailbox_maps = mysql:/etc/postfix/sql/mysql_virtual_mailbox_maps.cf, mysql:/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf"

postconf命令显示配置参数的实际值，更改配置参数值或显示有关Postfix邮件系统的其他配置信息。

本地传递代理会将收到的电子邮件传递到用户的邮箱。运行以下命令以将Dovecot LMTP服务设置为默认邮件传递传输：

sudo postconf -e "virtual_transport = lmtp:unix:private/dovecot-lmtp"

使用先前生成的“加密SSL证书”设置TL参数：

sudo postconf -e 'smtp_tls_security_level = may'
sudo postconf -e 'smtpd_tls_security_level = may'
sudo postconf -e 'smtp_tls_note_starttls_offer = yes'
sudo postconf -e 'smtpd_tls_loglevel = 1'
sudo postconf -e 'smtpd_tls_received_header = yes'

sudo postconf -e 'smtpd_tls_cert_file = /etc/letsencrypt/live/mail.myfreax.com/fullchain.pem'
sudo postconf -e 'smtpd_tls_key_file = /etc/letsencrypt/live/mail.myfreax.com/privkey.pem'

配置经过身份验证的SMTP设置并将身份验证移交给Dovecot：

sudo postconf -e 'smtpd_sasl_type = dovecot'
sudo postconf -e 'smtpd_sasl_path = private/auth'
sudo postconf -e 'smtpd_sasl_local_domain ='
sudo postconf -e 'smtpd_sasl_security_options = noanonymous'
sudo postconf -e 'broken_sasl_auth_clients = yes'
sudo postconf -e 'smtpd_sasl_auth_enable = yes'
sudo postconf -e 'smtpd_recipient_restrictions = permit_sasl_authenticated,permit_mynetworks,reject_unauth_destination'

我们还需要编辑Postfix主配置文件master.cf，并启用提交端口（587）和smtps端口（465）。

使用文本编辑器打开文件，然后取消注释/编辑以下几行：

/etc/postfix/master.cf

submission inet n       -       y       -       -       smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_reject_unlisted_recipient=no
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
#  -o smtpd_helo_restrictions=$mua_helo_restrictions
#  -o smtpd_sender_restrictions=$mua_sender_restrictions
#  -o smtpd_recipient_restrictions=
#  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING
smtps     inet  n       -       y       -       -       smtpd
  -o syslog_name=postfix/smtps
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
#  -o smtpd_reject_unlisted_recipient=no
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
#  -o smtpd_helo_restrictions=$mua_helo_restrictions
#  -o smtpd_sender_restrictions=$mua_sender_restrictions
#  -o smtpd_recipient_restrictions=
#  -o smtpd_relay_restrictions=permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING

重新启动后缀服务，以使更改生效。

sudo systemctl restart postfix

至此，您已经成功配置了Postfix服务。

配置鸽舍

在本部分中，我们将配置Dovecot以使其与我们的设置相匹配。确保编辑以黄色突出显示的行。

首先配置dovecot-sql.conf.ext文件，该文件指示Dovecot如何访问数据库以及如何找到有关电子邮件帐户的信息。

/etc/dovecot/dovecot-sql.conf.ext

driver = mysql
connect = host=127.0.0.1 dbname=postfixadmin user=postfixadmin password=P4ssvv0rD
default_pass_scheme = MD5-CRYPT
iterate_query = SELECT username AS user FROM mailbox
user_query = SELECT CONCAT('/var/mail/vmail/',maildir) AS home, \
  CONCAT('maildir:/var/mail/vmail/',maildir) AS mail, \
  5000 AS uid, 5000 AS gid, CONCAT('*:bytes=',quota) AS quota_rule \
  FROM mailbox WHERE username = '%u' AND active = 1
password_query = SELECT username AS user,password FROM mailbox \
  WHERE username = '%u' AND active='1'

请不要忘记使用正确的MySQL凭据（dbname，用户名和密码）。

接下来，编辑conf.d/10-mail.conf文件并编辑以下变量：

/etc/dovecot/conf.d/10-mail.conf

...
mail_location = maildir:/var/mail/vmail/%d/%n
...
mail_uid = vmail
mail_gid = vmail
...
first_valid_uid = 5000
last_valid_uid = 5000
...
mail_privileged_group = vmail
...
mail_plugins = quota
...

要进行身份验证，请打开conf.d/10-auth.conf，编辑以下行并包含auth-sql.conf.ext文件：

/etc/dovecot/conf.d/10-auth.conf

...
disable_plaintext_auth = yes
...
auth_mechanisms = plain login
...
#!include auth-system.conf.ext
!include auth-sql.conf.ext
...

打开conf.d/10-master.conf文件，并对其进行如下修改：

/etc/dovecot/conf.d/10-master.conf

...
service lmtp {
  unix_listener /var/spool/postfix/private/dovecot-lmtp {
    mode = 0600
    user = postfix
    group = postfix
  }
...
}
...
service auth {
  ...
  unix_listener auth-userdb {
    mode = 0600
    user = vmail
    group = vmail
  }
  ...
  unix_listener /var/spool/postfix/private/auth {
    mode = 0666
    user = postfix
    group = postfix
  }
  ...
}
...
service auth-worker {
  user = vmail
}
...
service dict {
  unix_listener dict {
    mode = 0660
    user = vmail
    group = vmail
  }
}
...

打开conf.d/10-ssl.conf并启用SSL / TLS。

/etc/dovecot/conf.d/10-ssl.conf

...
ssl = yes
...
ssl_cert = </etc/letsencrypt/live/mail.myfreax.com/fullchain.pem
ssl_key = </etc/letsencrypt/live/mail.myfreax.com/privkey.pem
ssl_dh = </etc/ssl/certs/dhparam.pem
...
ssl_cipher_list = EECDH+AES:EDH+AES+aRSA
...
ssl_prefer_server_ciphers = yes
...

请确保使用正确的SSL证书文件路径。

如果从一开始就遵循此系列，则应该已经拥有fullchain.pem，privkey.pem ，在您的服务器上创建的dhparam.pem个文件。有关如何创建免费的“让我们加密SSL证书和Diffie-Hellman密钥”的更多信息，请查看此教程。

感谢 Nevyn 来注意该问题并提供了一个解决方案。解决方案。

打开conf.d/20-imap.conf文件并激活imap_quota插件：

/etc/dovecot/conf.d/20-imap.conf

...
protocol imap {
  ...
  mail_plugins = $mail_plugins imap_quota
  ...
}
...

打开conf.d/20-lmtp.conf文件，然后进行如下编辑：

/etc/dovecot/conf.d/20-lmtp.conf

...
protocol lmtp {
  postmaster_address = postmaster@myfreax.com
  mail_plugins = $mail_plugins
}
...

在conf.d/20-lmtp.conf文件中定义默认邮箱：

/etc/dovecot/conf.d/15-mailboxes.conf

...
mailbox Drafts {
  special_use = \Drafts
}
mailbox Spam {
  special_use = \Junk
  auto = subscribe
}
mailbox Junk {
  special_use = \Junk
}
...

有两种不同类型的配额大小，一种是为整个域设置的，另一种是为每个用户邮箱设置的。在本系列的前一部分中，我们已经在PostfixAdmin中启用了配额支持，这意味着配额信息将存储在PostfixAdmin数据库中。

现在，我们需要配置Dovecot以连接到数据库，处理配额限制，并运行一个脚本，当用户的配额超过指定的限制时向用户发送邮件。为此，请打开conf.d/90-quota.conf文件并对其进行如下修改：

/etc/dovecot/conf.d/90-quota.conf

plugin {
  quota = dict:User quota::proxy::sqlquota
  quota_rule = *:storage=5GB
  quota_rule2 = Trash:storage=+100M
  quota_grace = 10%%
  quota_exceeded_message = Quota exceeded, please contact your system administrator.
  quota_warning = storage=100%% quota-warning 100 %u
  quota_warning2 = storage=95%% quota-warning 95 %u
  quota_warning3 = storage=90%% quota-warning 90 %u
  quota_warning4 = storage=85%% quota-warning 85 %u
}

service quota-warning {
  executable = script /usr/local/bin/quota-warning.sh
  user = vmail

  unix_listener quota-warning {
    group = vmail
  	mode = 0660
  	user = vmail
  }
}

dict {
  sqlquota = mysql:/etc/dovecot/dovecot-dict-sql.conf.ext
}

我们还需要告诉dovecot如何访问配额SQL词典。打开dovecot-dict-sql.conf.ext文件，然后编辑以下几行：

/etc/dovecot/dovecot-dict-sql.conf.ext

...
connect = host=127.0.0.1 dbname=postfixadmin user=postfixadmin password=P4ssvv0rD
...
map {
  pattern = priv/quota/storage
  table = quota2
  username_field = username
  value_field = bytes
}
map {
  pattern = priv/quota/messages
  table = quota2
  username_field = username
  value_field = messages
}
...
# map {
#   pattern = shared/expire/$user/$mailbox
#   table = expires
#   value_field = expire_stamp
#
#   fields {
#     username = $user
#     mailbox = $mailbox
#   }
# }
...

确保使用正确的MySQL凭据（dbname，用户名和密码）。

创建以下外壳程序脚本，如果其配额超过指定的限制，该脚本将向用户发送电子邮件：

/usr/local/bin/quota-warning.sh

#!/bin/sh
PERCENT=$1
USER=$2
cat << EOF | /usr/lib/dovecot/dovecot-lda -d $USER -o "plugin/quota=dict:User quota::noenforcing:proxy::sqlquota"
From: postmaster@myfreax.com
Subject: Quota warning

Your mailbox is now $PERCENT% full.
EOF

通过运行以下 chmod 命令使脚本可执行：

sudo chmod +x /usr/local/bin/quota-warning.sh

最后重新启动鸽舍服务，以使更改生效。

sudo systemctl restart dovecot

结论

到现在，您应该拥有一个功能齐全的邮件系统。在本系列的下一部分中，我们将向您展示如何安装和集成Rspamd 。

此信息是 设置和配置邮件服务器 系列的一部分。
该系列的其他信息：  

• 使用PostfixAdmin 设置邮件服务器

•安装和配置Postfix和Doveco

• 安装和集成Rspamd

• 安装和配置Roundcube网络邮件