错误如下：

31398 Apr 25 17:22:39 AY130531173153591e6cZ postfix/smtp[17402]: 761B4A041E: to=, relay=mx2.mail.aliyun.com[110.      75.48.150]:25, delay=0.12, delays=0.03/0/0.07/0.02, dsn=5.0.0, status=bounced (host mx2.mail.aliyun.com[110.75.48.150] said: 500       Error: bad syntax (in reply to MAIL FROM command))

重点是“in reply to MAIL FROM command”

需要修改outgoing mail address。

步骤如下：
1. 在 /etc/postfix/main.cf中加入

smtp_generic_maps = hash:/etc/postfix/generic

2. 生成generic文件

echo 'www-data yourusername@yourdomain.com' >> /etc/postfix/generic
newaliases

3. 重启postfix

postmap /etc/postfix/generic
service postfix restart