Linux - postfix - 用 GMAIL SMTP 送信

1. 安装

$ su

Ubuntu
$ apt install postfix mailutils mpack mutt

Fedora
$ dnf install postfix mailx mutt

CentOS
$ yum install postfix mailx mutt cyrus-sasl cyrus-sasl-plain

OpenSUSE
$ zypper install postfix mailx mutt cyrus-sasl

* mpack / mailx / mutt 可选择只安装一个

* Fedora / CentOS 建议先解决 SELINUX 问题
http://jasonmun.blogspot.my/2017/01/centos-fedora-postfix-selinux.html

2. 设置

$ gedit /etc/postfix/sasl_passwd

[smtp.gmail.com]:587 username@gmail.com:password

$ chmod 600 /etc/postfix/sasl_passwd

$ gedit /etc/postfix/main.cf

relayhost = [smtp.gmail.com]:587

smtp_sasl_auth_enable = yes
smtp_sasl_security_options =
smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd

smtp_use_tls = yes

Ubuntu
smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

Fedora / CentOS
smtp_tls_CAfile = /etc/ssl/certs/ca-bundle.crt

OpenSUSE
smtp_tls_CAfile = /etc/ssl/ca-bundle.pem

$ gedit /etc/postfix/master.cf

tlsmgr    unix  -       -       n       1000?   1       tlsmgr

3. 设置 - GOOGLE

i) Settings - Forwarding and POP/IMAP - IMAP Access - Enable IMAP
https://mail.google.com/mail/u/0/#settings/fwdandpop

ii) 修改步骤 2 的 password
Sign-in & security - Signing in to Google - 2-Step Verification - ON
Sign-in & security - Signing in to Google - App passwords
这个用 App Password

Sign-in & security - Signing in to Google - 2-Step Verification - Off
Sign-in & security - Connected apps & sites - Allow less secure apps: ON
这个用 Gmail Password

https://myaccount.google.com/security?utm_source=OGB#signin

4. 重启

$ postmap /etc/postfix/sasl_passwd
$ systemctl restart postfix

5. 在防火壁增加 PORT 25

Ubuntu
$ ufw allow Postfix

CentOS / Fedora
$ firewall-cmd --add-service=smtp --permanent
或
$ firewall-cmd --add-port=25/tcp --permanent
$ firewall-cmd --reload

OpenSUSE
YaST - Firewall - Allowed Services - Service to Allow : SMTP with Postfix - Add

6. 测试

$ echo "This is a test" | mail -s "Subject" recipient@yahoo.com
$ echo "This is a test" | mail -s "Subject" recipient@yahoo.com -A /home/user/content.txt

# OpenSUSE 用 mailx 要将 -a 改为 -A
$ echo "This is a test" | mailx -s "Subject" recipient@yahoo.com -a /home/user/content.txt
$ echo "This is a test" | mutt -s "Subject" recipient@yahoo.com -a /home/user/content.txt

$ mpack -s "Test File" /home/user/content.txt recipient@yahoo.com

7. 其它

Ubuntu - postfix - Host not found 解决方法

http://jasonmun.blogspot.my/2017/01/ubuntu-postfix-host-not-found.html