我在 VPS 上安装了 Postfix 和 Dovecot，并配置为将邮件转发到 Gmail 地址，并接受来自 gmail 的 smtp 请求，以便它可以代表该域发送。TLS 和身份验证正在工作，电子邮件正在到达，MX 域、SPR、DKIM、SPF，所有配置和工作。
但是，我只能向自己和少数域发送电子邮件。例如：
This is the mail system at host tomjn.com.
I'm sorry to have to inform you that your message could not
be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can
delete your own text from the attached returned message.
The mail system
<matt@geekmatt.com>: host dc-cd3425bc.geekmatt.com[87.106.180.26] said: …