HTML代码:

<form enctype="multipart/form-data" method="POST" action=""> 
    <label>Your Name <input type="text" name="sender_name" /> </label> 
    <label>Your Email <input type="email" name="sender_email" /> </label> 
    <label>Your Contact Number <input type="tel" name="contactnumber" /> </label>
    <label>Subject <input type="text" name="subject" /> </label> 
    <label>Message <textarea name="description"></textarea> </label> 
    <label>Attachment <input type="file" name="attachment" /></label> 
    <label><input type="submit" name="button" value="Submit" /></label> 
</form> 

PHP代码:

<?php
if($_POST['button']){
{
    //Server Variables
    $server_name = "Your Name";
    $server_mail = "your_mail@domain.com";

    //Name Attributes of HTML FORM
    $sender_email = "sender_email";
    $sender_name = "sender_name";
    $contact = "contactnumber";
    $mail_subject = "subject";
    $input_file = "attachment";
    $message = "description";

    //Fetching HTML Values
    $sender_name = $_POST[$sender_name];
    $sender_mail = $_POST[$sender_email];
    $message = $_POST[$message];
    $contact= $_POST[$contact];
    $mail_subject = $_POST[$mail_subject];

    //Checking if File is uploaded
    if(isset($_FILES[$input_file])) 
    { 
        //Main Content
        $main_subject = "Subject seen on server's mail";
        $main_body = "Hello $server_name,<br><br> 
        $sender_name ,contacted you through your website and the details are as below: <br><br> 
        Name : $sender_name <br> 
        Contact Number : $contact <br> 
        Email : $sender_mail <br> 
        Subject : $mail_subject <br> 
        Message : $message.";

        //Reply Content
        $reply_subject = "Subject seen on sender's mail";
        $reply_body = "Hello $sender_name,<br> 
        \t Thank you for filling the contact form. We will revert back to you shortly.<br><br>
        This is an auto generated mail sent from our Mail Server.<br>
        Please do not reply to this mail.<br>
        Regards<br>
        $server_name";

//#############################DO NOT CHANGE ANYTHING BELOW THIS LINE#############################
        $filename= $_FILES[$input_file]['name'];
        $file = chunk_split(base64_encode(file_get_contents($_FILES[$input_file]['tmp_name'])));
        $uid = md5(uniqid(time()));
        //Sending mail to Server
        $retval = mail($server_mail, $main_subject, "--$uid\r\nContent-type:text/html; charset=iso-8859-1\r\nContent-Transfer-Encoding: 7bit\r\n\r\n $main_body \r\n\r\n--$uid\r\nContent-Type: application/octet-stream; name=\"$filename\"\r\nContent-Transfer-Encoding: base64\r\nContent-Disposition: attachment; filename=\"$filename\"\r\n\r\n$file\r\n\r\n--$uid--", "From: $sender_name <$sender_mail>\r\nReply-To: $sender_mail\r\nMIME-Version: 1.0\r\nContent-Type: multipart/mixed; boundary=\"$uid\"\r\n\r\n");
        //Sending mail to Sender
        $retval = mail($sender_mail, $reply_subject, $reply_body , "From: $server_name<$server_mail>\r\nMIME-Version: 1.0\r\nContent-type: text/html\r\n");
//#############################DO NOT CHANGE ANYTHING ABOVE THIS LINE#############################

        //Output
        if ($retval == true) {
            echo "Message sent successfully...";
            echo "<script>window.location.replace('index.html');</script>";
        } else {
            echo "Error<br>";
            echo "Message could not be sent...Try again later";
            echo "<script>window.location.replace('index.html');</script>";
        }
    }else{
        echo "Error<br>";
        echo "File Not Found";
    }
}else{
    echo "Error<br>";
    echo "Unauthorised Access";
}

要发送带有附件的电子邮件，我们需要使用multipart/mixed MIME类型，该类型指定混合类型将包含在电子邮件中。此外，我们希望使用多部分/替代MIME类型来发送纯文本和HTML版本的电子邮件。看一下这个例子:

<?php 
//define the receiver of the email 
$to = 'youraddress@example.com'; 
//define the subject of the email 
$subject = 'Test email with attachment'; 
//create a boundary string. It must be unique 
//so we use the MD5 algorithm to generate a random hash 
$random_hash = md5(date('r', time())); 
//define the headers we want passed. Note that they are separated with \r\n 
$headers = "From: webmaster@example.com\r\nReply-To: webmaster@example.com"; 
//add boundary string and mime type specification 
$headers .= "\r\nContent-Type: multipart/mixed; boundary=\"PHP-mixed-".$random_hash."\""; 
//read the atachment file contents into a string,
//encode it with MIME base64,
//and split it into smaller chunks
$attachment = chunk_split(base64_encode(file_get_contents('attachment.zip'))); 
//define the body of the message. 
ob_start(); //Turn on output buffering 
?> 
--PHP-mixed-<?php echo $random_hash; ?>  
Content-Type: multipart/alternative; boundary="PHP-alt-<?php echo $random_hash; ?>" 

--PHP-alt-<?php echo $random_hash; ?>  
Content-Type: text/plain; charset="iso-8859-1" 
Content-Transfer-Encoding: 7bit

Hello World!!! 
This is simple text email message. 

--PHP-alt-<?php echo $random_hash; ?>  
Content-Type: text/html; charset="iso-8859-1" 
Content-Transfer-Encoding: 7bit

<h2>Hello World!</h2> 
<p>This is something with <b>HTML</b> formatting.</p> 

--PHP-alt-<?php echo $random_hash; ?>-- 

--PHP-mixed-<?php echo $random_hash; ?>  
Content-Type: application/zip; name="attachment.zip"  
Content-Transfer-Encoding: base64  
Content-Disposition: attachment  

<?php echo $attachment; ?> 
--PHP-mixed-<?php echo $random_hash; ?>-- 

<?php 
//copy current buffer contents into $message variable and delete current output buffer 
$message = ob_get_clean(); 
//send the email 
$mail_sent = @mail( $to, $subject, $message, $headers ); 
//if the message is sent successfully print "Mail sent". Otherwise print "Mail failed" 
echo $mail_sent ? "Mail sent" : "Mail failed"; 
?>

正如你所看到的，发送带有附件的电子邮件很容易完成。在前面的例子中，我们有多部分/混合MIME类型，在里面我们有多部分/替代MIME类型，指定两个版本的电子邮件。为了将附件包含到消息中，我们将指定文件中的数据读入一个字符串，使用base64对其进行编码，将其分割为更小的块，以确保它与MIME规范匹配，然后将其作为附件包含。

从这里拍的。

            $to = "to@gmail.com";
            $subject = "Subject Of The Mail";
            $message = "Hi there,<br/><br/>This is my message.<br><br>";

            $headers = "From: From-Name<from@gmail.com>";
// boundary
            $semi_rand = md5(time());
            $mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";

// headers for attachment
            $headers .= "\nMIME-Version: 1.0\n" . "Content-Type: multipart/mixed;\n" . " boundary=\"{$mime_boundary}\"";

// multipart boundary
            $message = "This is a multi-part message in MIME format.\n\n" . "--{$mime_boundary}\n" . "Content-Type: text/html; charset=ISO-8859-1\"\n" . "Content-Transfer-Encoding: 7bit\n\n" . $message . "\n\n";

                $message .= "--{$mime_boundary}\n";
                $filepath = 'uploads/'.$_FILES['image']['name'];
                move_uploaded_file($_FILES['image']['tmp_name'], $filepath); //upload the file
                $filename = $_FILES['image']['name'];
                $file = fopen($filepath, "rb");
                $data = fread($file, filesize($filepath));
                fclose($file);
                $data = chunk_split(base64_encode($data));
                $message .= "Content-Type: {\"application/octet-stream\"};\n" . " name=\"$filename\"\n" .
                        "Content-Disposition: attachment;\n" . " filename=\"$filename\"\n" .
                        "Content-Transfer-Encoding: base64\n\n" . $data . "\n\n";
                $message .= "--{$mime_boundary}\n";

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

我同意评论中的@MihaiIorga -使用PHPMailer脚本。听起来你拒绝是因为你想要更简单的选择。相信我，比起自己使用PHP内置的mail()函数，PHPMailer是一个更简单的选择。PHP的mail()函数真的不是很好。

使用PHPMailer:

下载PHPMailer脚本:http://github.com/PHPMailer/PHPMailer 提取归档文件并将脚本文件夹复制到项目中方便的位置。 包括主脚本文件——require_once('path/to/file/class.phpmailer.php');

现在，发送带有附件的电子邮件从异常困难变得异常简单:

use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;

$email = new PHPMailer();
$email->SetFrom('you@example.com', 'Your Name'); //Name is optional
$email->Subject   = 'Message Subject';
$email->Body      = $bodytext;
$email->AddAddress( 'destinationaddress@example.com' );

$file_to_attach = 'PATH_OF_YOUR_FILE_HERE';

$email->AddAttachment( $file_to_attach , 'NameOfFile.pdf' );

return $email->Send();

只有一行$email-> addatattachment ();——再简单不过了。

如果使用PHP的mail()函数，则需要编写大量代码，并且可能会遇到许多很难找到的错误。

这对我很有用。它还附加了多个附件。很容易

<?php

if ($_POST && isset($_FILES['file'])) {
    $recipient_email = "recipient@yourmail.com"; //recepient
    $from_email = "info@your_domain.com"; //from email using site domain.
    $subject = "Attachment email from your website!"; //email subject line

    $sender_name = filter_var($_POST["s_name"], FILTER_SANITIZE_STRING); //capture sender name
    $sender_email = filter_var($_POST["s_email"], FILTER_SANITIZE_STRING); //capture sender email
    $sender_message = filter_var($_POST["s_message"], FILTER_SANITIZE_STRING); //capture message
    $attachments = $_FILES['file'];

    //php validation
    if (strlen($sender_name) < 4) {
        die('Name is too short or empty');
    }
    if (!filter_var($sender_email, FILTER_VALIDATE_EMAIL)) {
        die('Invalid email');
    }
    if (strlen($sender_message) < 4) {
        die('Too short message! Please enter something');
    }

    $file_count = count($attachments['name']); //count total files attached
    $boundary = md5("specialToken$4332"); // boundary token to be used

    if ($file_count > 0) { //if attachment exists
        //header
        $headers = "MIME-Version: 1.0\r\n";
        $headers .= "From:" . $from_email . "\r\n";
        $headers .= "Reply-To: " . $sender_email . "" . "\r\n";
        $headers .= "Content-Type: multipart/mixed; boundary = $boundary\r\n\r\n";

        //message text
        $body = "--$boundary\r\n";
        $body .= "Content-Type: text/plain; charset=ISO-8859-1\r\n";
        $body .= "Content-Transfer-Encoding: base64\r\n\r\n";
        $body .= chunk_split(base64_encode($sender_message));

        //attachments
        for ($x = 0; $x < $file_count; $x++) {
            if (!empty($attachments['name'][$x])) {

                if ($attachments['error'][$x] > 0) { //exit script and output error if we encounter any
                    $mymsg = array(
                        1 => "The uploaded file exceeds the upload_max_filesize directive in php.ini",
                        2 => "The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form",
                        3 => "The uploaded file was only partially uploaded",
                        4 => "No file was uploaded",
                        6 => "Missing a temporary folder");
                    die($mymsg[$attachments['error'][$x]]);
                }

                //get file info
                $file_name = $attachments['name'][$x];
                $file_size = $attachments['size'][$x];
                $file_type = $attachments['type'][$x];

                //read file 
                $handle = fopen($attachments['tmp_name'][$x], "r");
                $content = fread($handle, $file_size);
                fclose($handle);
                $encoded_content = chunk_split(base64_encode($content)); //split into smaller chunks (RFC 2045)

                $body .= "--$boundary\r\n";
                $body .= "Content-Type: $file_type; name=" . $file_name . "\r\n";
                $body .= "Content-Disposition: attachment; filename=" . $file_name . "\r\n";
                $body .= "Content-Transfer-Encoding: base64\r\n";
                $body .= "X-Attachment-Id: " . rand(1000, 99999) . "\r\n\r\n";
                $body .= $encoded_content;
            }
        }
    } else { //send plain email otherwise
        $headers = "From:" . $from_email . "\r\n" .
                "Reply-To: " . $sender_email . "\n" .
                "X-Mailer: PHP/" . phpversion();
        $body = $sender_message;
    }

    $sentMail = @mail($recipient_email, $subject, $body, $headers);
    if ($sentMail) { //output success or failure messages
        die('Thank you for your email');
    } else {
        die('Could not send mail! Please check your PHP mail configuration.');
    }
}
?>

在与格式糟糕的附件斗争了一段时间后，我使用了以下代码:

$email = new PHPMailer();
$email->From      = 'from@somedomain.com';
$email->FromName  = 'FromName';
$email->Subject   = 'Subject';
$email->Body      = 'Body';
$email->AddAddress( 'to@somedomain.com' );
$email->AddAttachment( "/path/to/filename.ext" , "filename.ext", 'base64', 'application/octet-stream' );
$email->Send();