smtp 发送邮件乱码

$header .= "Subject: ".$subject."\r\n";

TO

$header .= "Subject: "."=?UTF-8?B?".base64_encode($subject)."?="."\r\n";

$header = "MIME-Version:1.0\r\n";

TO

$header = "MIME-Version:1.0\r\n";
$header .= "Content-type: text/plain; charset=utf-8\r\n";
$header .= "Content-Transfer-Encoding: 8bit\r\n";