php - 警告 : mail() expects parameter 4 to be string

Question

我正在尝试使用以下代码发送邮件，但出现以下错误
没有mail()接受标题的数组？

Warning: mail() expects parameter 4 to be string, array given in ../email.php on line 16

代码 :

<?php
$name       = @trim(stripslashes($_POST['name'])); 
$from       = @trim(stripslashes($_POST['email'])); 
$subject    = @trim(stripslashes($_POST['subject'])); 
$message    = @trim(stripslashes($_POST['message'])); 
$to         = 'example@gmail.com';

$headers   = array();
$headers[] = "MIME-Version: 1.0";
$headers[] = "Content-type: text/plain; charset=iso-8859-1";
$headers[] = "From: {$name} <{$from}>";
$headers[] = "Reply-To: <{$from}>";
$headers[] = "Subject: {$subject}";
$headers[] = "X-Mailer: PHP/".phpversion();

mail($to, $subject, $message, $headers);

Answer 1

PHP mail()需要string $to , string $subject , string $message , string $headers
如果你想使用一个数组作为标题

mail($to, $subject, $message, implode("\r\n", $headers));

否则更改您的代码

$headers  = "MIME-Version: 1.0\r\n";
$headers .= "Content-type: text/plain; charset=iso-8859-1\r\n";
$headers .= "From: {$name} <{$from}>\r\n";
$headers .= "Reply-To: <{$from}>\r\n";
$headers .= "Subject: {$subject}\r\n";
$headers .= "X-Mailer: PHP/".phpversion()."\r\n";

为什么\r\n (来自 mail() 文档)？

Multiple extra headers should be separated with a CRLF (\r\n) [...] If messages are not received, try using a LF (\n) only. Some Unix mail transfer agents (most notably » qmail) replace LF by CRLF automatically (which leads to doubling CR if CRLF is used). This should be a last resort, as it does not comply with » RFC 2822.

边注用途"\r\n"而不是 '\r\n'