MIME在PHP邮件功能标题中的作用是什么

有人可以让我知道MIME-Version：1.0在PHP HTML mail()函数中的作用是什么以及为什么要使用它？我已经谷歌了,但无法找到明确的解释？

// Always set content-type when sending HTML email
$headers = "MIME-Version: 1.0" . "\r\n";
$headers .= "Content-type:text/html;charset=UTF-8" . "\r\n";

谢谢

解决方法:

mime-version理论上允许引入MIME的更新,但实际上它没有使用,并且总是设置为1.0.由于根据MIME规范设置版本是必需的,因此您必须包含它.

见维基百科：http://en.wikipedia.org/wiki/MIME#MIME-Version

According to MIME co-creator Nathaniel Borenstein, the intention was
to allow MIME to change, to advance to version 2.0 and so forth, but
this decision led to the opposite outcome, making it nearly impossible
to create a new version of the standard.

“We did not adequately specify how to handle a future MIME version,”
Borenstein said. “So if you write something that knows 1.0, what
should you do if you encounter 2.0 or 1.1? I sort of thought it was
obvious but it turned out everyone implemented that in different ways.
And the result is that it would be just about impossible for the
Internet to ever define a 2.0 or a 1.1.”

标签：php,mime,html-email
来源： https://codeday.me/bug/20190628/1319228.html