更新日: 2023-06-11 21:31

Postfix でメールサーバー

Postfix Ubuntu OpenDKIM OpenDMARC

Postfix install
Dovecot install

Postfix をUbuntu 20.04 にインストールします。

Postfix install

apt install postfix

Internet Site を選び、メールドメインを設定する。

main.cf

vi /etc/postfix/main.cf

myhostname = mail.mydomain.com
mynetworks= 192.168.0.0/16  #Add
mydestination =

# これが無いと送信済みトレイへの保存に失敗する?
home_mailbox = Maildir/

Virtual mailbox domain を使う。

groupadd -g 5000 vmail
useradd -g 5000 -u 5000 -s /sbin/nologin -m vmail
chmod 700 /home/vmail

vmaildir にメールアドレスと保存先のペアを設定。

vi /etc/postfix/vmaildir

ast@mydomain.com mydomain.com/ast/Maildir/
test2@mydomain2.com mydomain2.com/test2/Maildir/

# 更新後は再変換。
postmap /etc/postfix/vmailder

main.cf にvirtual_mailbox_domains を設定

# temp
home_mailbox = Maildir/

# Virtual Mailbox
virtual_mailbox_domains = qt-space.com, mydomains.com
virtual_mailbox_base = /home/vmail
virtual_mailbox_maps = hash:/etc/postfix/vmaildir
virtual_minimum_uid = 100
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000

メール受信テスト。受信すると/home/vmail 以下にフォルダが作成される。

// 127.0.0.1 に向けて届くように一時的に詐称する

vi /etc/hosts

127.0.0.1  mail.mydomain.com mail.mydomain2.com

echo "TEST" | mail -s "test1" -r "ast@mydomain.com" "ast@mydomain.com"

less /var/log/mail.log

Virtual domain HELO

SMTP 送信時のHELO を、メール送信元ドメインに応じて変える(SPAM 対策)

vi /etc/postfix/sender_dependent_default_transport_maps

@mydomain.com   out_mydomain_com:
@mydomain2.com    out_mydomain2_com:

# convert
postmap /etc/postfix/sender_dependent_default_transport_maps

main.cf

vi /etc/postfix/main.cf

#Virtual Domain HELO
sender_dependent_default_transport_maps = hash:/etc/postfix/sender_dependent_default_transport_maps

master.cf

vi /etc/postfix/master.cf

# Add (virtual domain helo)
out_mydomain_com unix  - - n - - smtp -o smtp_helo_name=mail.mydomain.com
out_mydomain2_com unix  - - n - - smtp -o smtp_helo_name=mail.mydomain2.com

Dovecot install

IMAP を使います。

apt install dovecot-imapd

dovecot.conf

vi /etc/dovecot/dovecot.conf

listen = *, ::
login_greeting = ready.
login_trusted_networks = 127.0.0.1/8 192.168.0.0/16

10-mail.conf

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

# mail_location = mbox:~/mail:INBOX=/var/mail/%u

## /home/vmail/qt-space.com/ast/Maildir
mail_location = /home/vmail/%d/%n/Maildir:LAYOUT=fs

10-master.conf

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

service imap-login {
  inet_listener imap {
    port = 143
  }
  inet_listener imaps {
  port = 993
    ssl = yes
}

10-auth.conf

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

// プレーンテキスト認証は無効（login_trusted_networks, SSL/TLS は除く)
disable_plaintext_auth = yes

// 平文及びCRAM-MD5 で認証
auth_mechanisms = plain cram-md5

#!include auth-system.conf.ext
!include auth-passwdfile.conf.ext
!include auth-static.conf.ext

認証に使うパスワードファイルの場所を設定します。

auth-passwdfile.conf.ext

vi /etc/dovecot/conf.d/auth-passwdfile.conf.ext

passdb {
  driver = passwd-file
  #args = scheme=CRYPT username_format=%u /etc/dovecot/users
  args = scheme=CRAM-MD5 username_format=%u /etc/dovecot/passwd
}
userdb {
  driver = passwd-file
  #args = username_format=%u /etc/dovecot/users
  # scheme=CRAM-MD5 を含めるとエラーになります！
  args = username_format=%u /etc/dovecot/passwd
}

メールアカウントとパスワードを /etc/dovecot/passwd というファイルで管理します。

doveadm pw -s CRAM-MD5

vi /etc/dovecot/passwd
test@qt-space.com:{CRAM-MD5}abcdefg0123456abcdefg0123456

auth-static.conf.ext

vi /etc/dovecot/conf.d/auth-static.conf.ext

userdb {
  driver = static
  #args = uid=vmail gid=vmail home=/home/%u
  args = uid=vmail gid=vmail home=/home/vmail/%d/%n
}

SSL(Let's encrypt) を使う。

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

ssl = yes
ssl_cert = </etc/postfix/keys/mail.mydomain.com/fullchain.pem
ssl_key  = </etc/postfix/keys/mail.mydomain.com/privkey.pem

10-logging.conf

vi /etc/dovecot/conf.d/10-logging.conf

log_path = /var/log/dovecot/dovecot.log

# mkdir /var/log/dovecot

SMTP-AUTH を使う

main.cf

vi /etc/postfix/main.cf

#SMTP-AUTH
#smtpd default settings.
# VRFY command is user exists check.
disable_vrfy_command = yes
smtpd_helo_required = yes
smtpd_sasl_auth_enable = yes
smtpd_sasl_authenticated_header = yes
smtpd_sasl_path = private/auth
smtpd_sasl_security_options = noanonymous, noplaintext
smtpd_sasl_local_domain = $myhostname
smtpd_sasl_type = dovecot
# permit_mynetworks(Allow mynetworks), permit_sasl_authenticated(Allow SASL success)
# reject_unauth_destination(Deny SASL false)
# reject_unknown_sender_domain(Deny From none exist domain)
# reject_non_fqdn_sender(Deny Not fqdn sender address)
# otherwise = True
smtpd_recipient_restrictions = permit_mynetworks,permit_sasl_authenticated,reject_unauth_destination,reject_unknown_sender_domain,reject_non_fqdn_sender
#broken_sasl_auth_clients = yes

10-master.conf

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

service auth {

  # Postfix smtp-auth
  unix_listener /var/spool/postfix/private/auth {
    mode = 0666
    user = postfix
    group = postfix
  }
}

Submission port 587 を使う

vi /etc/postfix/master.cf

submission  inet  n  -  y  -  -  smtpd
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=$mua_client_restrictions

SMTPS を使う

vi /etc/postfix/main.cf

#Use SMTPS from other MTA to Postfix
smtpd_tls_security_level = may
smtpd_tls_loglevel = 1
smtpd_tls_cert_file = /etc/postfix/keys/mail.mydomain.com/fullchain.pem
smtpd_tls_key_file  = /etc/postfix/keys/mail.mydomain.com/privkey.pem
smtpd_tls_session_cache_database = btree:/var/lib/postfix/smtpd_scache
smtpd_tls_received_header = yes

master.cf

vi /etc/postfix/master.cf

smtps  inet  n  -  y -  -  smtpd
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_recipient_restrictions=permit_sasl_authenticated,reject