由于它们指定的附件格式(application/octet-stream)，上面的答案都不适合我。使用application/pdf可获得pdf文件的最佳效果。

<?php

// just edit these 
$to          = "email1@domain.com, email2@domain.com"; // addresses to email pdf to
$from        = "sent_from@domain.com"; // address message is sent from
$subject     = "Your PDF email subject"; // email subject
$body        = "<p>The PDF is attached.</p>"; // email body
$pdfLocation = "./your-pdf.pdf"; // file location
$pdfName     = "pdf-file.pdf"; // pdf file name recipient will get
$filetype    = "application/pdf"; // type

// creates headers and mime boundary
$eol = PHP_EOL;
$semi_rand     = md5(time());
$mime_boundary = "==Multipart_Boundary_$semi_rand";
$headers       = "From: $from$eolMIME-Version: 1.0$eol" .
    "Content-Type: multipart/mixed;$eol boundary=\"$mime_boundary\"";

// add html message body
$message = "--$mime_boundary$eol" .
    "Content-Type: text/html; charset=\"iso-8859-1\"$eol" .
    "Content-Transfer-Encoding: 7bit$eol$eol$body$eol";

// fetches pdf
$file = fopen($pdfLocation, 'rb');
$data = fread($file, filesize($pdfLocation));
fclose($file);
$pdf = chunk_split(base64_encode($data));

// attaches pdf to email
$message .= "--$mime_boundary$eol" .
    "Content-Type: $filetype;$eol name=\"$pdfName\"$eol" .
    "Content-Disposition: attachment;$eol filename=\"$pdfName\"$eol" .
    "Content-Transfer-Encoding: base64$eol$eol$pdf$eol--$mime_boundary--";

// Sends the email
if(mail($to, $subject, $message, $headers)) {
    echo "The email was sent.";
}
else {
    echo "There was an error sending the mail.";
}

            $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);

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。

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();

你可以使用我创建的这个类发送常规邮件或附件邮件。

下面是如何使用它的示例链接。

https://github.com/Nerdtrix/EZMAIL

100%工作概念发送电子邮件与附件在php:

if (isset($_POST['submit'])) {
  extract($_POST);
  require_once('mail/class.phpmailer.php');

  $subject = "$name Applied For - $position";
  $email_message = "<div>Thanks for Applying ....</div> ";

  $mail = new PHPMailer;
  $mail->IsSMTP(); // telling the class to use SMTP
  $mail->Host = "mail.companyname.com"; // SMTP server
  $mail->SMTPDebug = 0;
  $mail->SMTPAuth = true;
  $mail->SMTPSecure = "ssl";
  $mail->Host = "smtp.gmail.com";
  $mail->Port = 465;
  $mail->IsHTML(true);
  $mail->Username = "info@companyname.com";  // GMAIL username
  $mail->Password = "mailPassword";          // GMAIL password

  $mail->SetFrom('info@companyname.com', 'new application submitted');
  $mail->AddReplyTo("name@yourdomain.com","First Last");
  $mail->Subject = "your subject";

  $mail->AltBody = "To view the message, please use an HTML compatible email viewer!"; // optional, comment out and test

  $mail->MsgHTML($email_message);

  $address = 'info@companyname.com';
  $mail->AddAddress($address, "companyname");

  $mail->AddAttachment($_FILES['file']['tmp_name'], $_FILES['file']['name']);      // attachment

  if (!$mail->Send()) {
    /* Error */
    echo 'Message not Sent! Email at info@companyname.com';
  } else {
    /* Success */
    echo 'Sent Successfully! <b> Check your Mail</b>';
  }
}

我使用此代码谷歌smtp邮件发送附件....

注意:下载PHPMailer库从这里-> https://github.com/PHPMailer/PHPMailer