I have the following headers that I want to pass to the mail() function:
$headers = "MIME-Version: 1.0
";
$headers .= "X-Mailer: PHP/" . phpversion()."
";
$headers .= "From:".$sender_email."
";
$headers .= "Subject:".$subject."
";
$headers .= "Reply-To: ".$sender_email."" . "
";
$headers .= "Content-Type: multipart/mixed; boundary=".md5('boundary1')."
";
$headers .= "--".md5('boundary1')."
";
$headers .= "Content-Type: multipart/alternative; boundary=".md5('boundary2')."
";
$headers .= "--".md5('boundary2')."
";
$headers .= "Content-Type: text/plain; charset=ISO-8859-1
";
$headers .= $message."
";
$headers .= "--".md5('boundary2')."--
";
$headers .= "--".md5('boundary1')."
";
$headers .= "Content-Type: ".$file_type."; ";
$headers .= "name=\"".$file_name."\"
";
$headers .= "Content-Transfer-Encoding:base64
";
$headers .= "Content-Disposition:attachment; ";
$headers .= "filename=\"".$file_name."\"
";
$headers .= "X-Attachment-Id:".rand(1000,9000)."
";
$headers .= $encoded_content."
";
$headers .= "--".md5('boundary1')."--";
$sentMail = @mail($recipient_email, $subject, $message, $headers);
Since I don't require the user to provide an e-mail address, can i exclude the "From" and Reply-To" fields and let the server auto-complete those values or would this action result in a malformed headers?
The server will automatically fill in the From line. Depending on the OS, it either gets the default From header from php.ini or from the username that runs PHP (e.g. www-user@yourdomain.com).
By default there's no Reply-to, so replies are sent to the From address. This header is only needed when you want replies to go to a different address, so in your case there's no need for it.
If no replies are wanted you could let it default, but a common approach is to put an address like NoReply@yourdomain.com in the From line. This way, if they do reply, they'll get a bounce message saying that the account doesn't exist.
You're also putting the message body into $headers, which isn't right. It's working because you also put a blank line before them -- that's treated as the separator between the headers and the message, so everything after that is actually sent in the body. But you shouldn't depend on this, so those lines should be sent as the message argument in mail().
$headers = "MIME-Version: 1.0
";
$headers .= "X-Mailer: PHP/" . phpversion()."
";
$headers .= "From: NoReply@yourdomain.com
";
$headers .= "Subject:".$subject."
";
$headers .= "Content-Type: multipart/mixed; boundary=".md5('boundary1')."
";
$body= "--".md5('boundary1')."
";
$body .= "Content-Type: multipart/alternative; boundary=".md5('boundary2')."
";
$body .= "--".md5('boundary2')."
";
$body .= "Content-Type: text/plain; charset=ISO-8859-1
";
$body .= $message."
";
$body .= "--".md5('boundary2')."--
";
$body .= "--".md5('boundary1')."
";
$body .= "Content-Type: ".$file_type."; ";
$body .= "name=\"".$file_name."\"
";
$body .= "Content-Transfer-Encoding:base64
";
$body .= "Content-Disposition:attachment; ";
$body .= "filename=\"".$file_name."\"
";
$body .= "X-Attachment-Id:".rand(1000,9000)."
";
$body .= $encoded_content."
";
$body .= "--".md5('boundary1')."--";
$sentMail = @mail($recipient_email, $subject, $body, $headers);
There also seems to be no reason for multipart/alternative in the first body section, since you're not sending multiple versions of $message.