PHP 邮件 : What does -f do?

Question

在对电子邮件主机的联系表单进行故障排除时，他们告诉我在 php 邮件功能的发件人地址中使用“-f”。 “-f”标志的作用是什么？为什么它可以解决允许发送电子邮件的问题？我阅读了一些文档，但不是很清楚。

示例代码:

mail($emailAddress, $mailSubject, $mailBody, $headers, '-f ' . $mailFrom);

PS:如果没有“-f”，它对大型电子邮件主机(hotmail、gmail 等，但出于某种原因不适用于我正在使用的小型主机)来说效果很好

谢谢

Answer 1

-f 是邮件程序(通常是 sendmail)的参数。来自 the docs :

The additional_parameters parameter can be used to pass additional flags as command line options to the program configured to be used when sending mail, as defined by the sendmail_path configuration setting. For example, this can be used to set the envelope sender address when using sendmail with the -f sendmail option.

这是 man page for sendmail ，您可以看到 -f 选项的作用:

-fname           Sets the name of the ``from'' person (i.e., the sender of the
                 mail).  -f can only be used by ``trusted'' users (normally
                 root, daemon, and network) or if the person you are trying to
                 become is the same as the person you are.