安装和配置Postfix和Dovecot
这是我们设置和配置邮件服务器系列的第二篇文章。
在这篇文章中，我们将向我们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，但是对任何较新版本的Ubuntu都可以进行相同的步骤，但稍加修改即可。
准备工作
在继续本教程之前，请确保我们以具有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 updatesudo 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如何访问在本系列的第一部分中创建的MySQL数据库。
sudo mkdir -p /etc/postfix/sql
打开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括有关存储在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，更改配置参数值或者显示有关Postfix邮件系统的其他配置信息。
本地传递代理会将传入的电子邮件传递到用户的邮箱。
运行以下命令，将Dovecot的LMTP服务设置为默认邮件传递传输方式：
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.theitroad.com/fullchain.pem'sudo postconf -e 'smtpd_tls_key_file = /etc/letsencrypt/live/mail.theitroad.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，我们已经成功配置了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查找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'
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 ...
要使身份验证有效，请打开“ conf.d/10-auth.conf”，编辑以下几行，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.theitroad.com/fullchain.pem ssl_key = </etc/letsencrypt/live/mail.theitroad.com/privkey.pem ssl_dh = </etc/ssl/certs/dhparam.pem ... ssl_cipher_list = EECDH+AES:EDH+AES+aRSA ... ssl_prefer_server_ciphers = yes ...
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，则应该已经在服务器上创建了“ fullchain.pem”，“ privkey.pem”，“ dhparam.pem”文件。
有关如何创建免费的“Let’s Encrypt SSL证书”和Diffie-Hellman密钥的更多信息，请查看本教程。
感谢Nevyn注意到问题并提供了解决方案。
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，并按如下所示进行编辑：
/etc/dovecot/conf.d/20-lmtp.conf
...
protocol lmtp {
postmaster_address = [email protected]
mail_plugins = $mail_plugins
}
...
在“ conf.d/20-lmtp.conf”文件中定义默认邮箱：
/etc/dovecot/conf.d/15-mailboxes.conf
...
mailbox Drafts {
special_use = \Drafts
}
mailbox Spam {
special_use = \Junk
auto = subscribe
}
mailbox Junk {
special_use = \Junk
}
...
有两种不同类型的配额大小，一种是为整个域设置的，另一种是为每个用户邮箱设置的。
在本系列的上一部分中，我们已经在PostfixAdmin中启用了配额支持，这意味着配额信息将存储在PostfixAdmin数据库中。
现在，我们需要配置Dovecot以连接到数据库，处理配额限制，并运行一个脚本，当用户的配额超过指定的限制时，该脚本向用户发送邮件。
为此，请打开“ conf.d/90-quota.conf”文件，并进行如下修改：
/etc/dovecot/conf.d/90-quota.conf
plugin {
quota = dict:User quota::proxy::sqlquota
quota_rule = *:storage=5GB
quota_rule2 = Trash:storage=+100M
quota_grace = 10%%
quota_exceeded_message = Quota exceeded, please contact your system administrator.
quota_warning = storage=100%% quota-warning 100 %u
quota_warning2 = storage=95%% quota-warning 95 %u
quota_warning3 = storage=90%% quota-warning 90 %u
quota_warning4 = storage=85%% quota-warning 85 %u
}
service quota-warning {
executable = script /usr/local/bin/quota-warning.sh
user = vmail
unix_listener quota-warning {
group = vmail
mode = 0660
user = vmail
}
}
dict {
sqlquota = mysql:/etc/dovecot/dovecot-dict-sql.conf.ext
}
我们还需要告诉dovecot如何访问配额SQL词典。
打开“ dovecot-dict-sql.conf.ext”文件，然后编辑以下几行：
/etc/dovecot/dovecot-dict-sql.conf.ext
...
connect = host=127.0.0.1 dbname=postfixadmin user=postfixadmin password=P4ssvv0rD
...
map {
pattern = priv/quota/storage
table = quota2
username_field = username
value_field = bytes
}
map {
pattern = priv/quota/messages
table = quota2
username_field = username
value_field = messages
}
...
# map {
# pattern = shared/expire/$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shell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= USER= cat << EOF | /usr/lib/dovecot/dovecot-lda -d $USER -o "plugin/quota=dict:User quota::noenforcing:proxy::sqlquota" From: [email protected] 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dovecot服务，以使更改生效。
sudo systemctl restart dovecot
