SimpleInvoicesEmailPHPmail

//Define types of messages. For the use of simpleinvoices, only html messages will be sent.
$htmlbody =
"
<h3>INVOICE</h3>
<br />
---------------------------------------------------------
<br />
Invoice Summary
<br />
---------------------------------------------------------
<br />
Invoice ID:
"
.
$invoice['index_id']
.
"
<br />
Issue Date:
"
.
$invoice['date']
.
"
<br />
Customer:
"
.
$customer['name']
.
"
<br />
Amount:
"
.
'$'.round($invoice['total'], 2)
.
"
<br />
Due:
"
.
'15 days from '.$invoice['date'].' (Net 15)'
.

"
<br />
Notes:
"
.
$invoice['note']
.
"
<br />
<br />
A detailed invoice is attached as a PDF.
<br />
<br />
"
.
"
----------------------------------------------------------
<br />
"
.
$_POST['email_notes'];

$textmessage = $_POST['email_notes'];
//define the receiver of the email
$to = $_POST['email_to'];
//define the subject of the email
$subject = $_POST['email_subject'];
//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: " . $biller['name'] . "<" . $_POST['email_from'] . ">" . "\r\nReply-To: " . $_POST['email_from'] . "\r\nBcc: " . $_POST['email_bcc'];
//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('./tmp/cache/' . $pdf_file_name))); ;
//define the body of the message.
$message = "--PHP-mixed-$random_hash\r\n"
."Content-Type: multipart/alternative; boundary=\"PHP-alt-$random_hash\"\r\n\r\n";
$message .= "--PHP-alt-$random_hash\r\n"
."Content-Type: text/plain; charset=\"iso-8859-1\"\r\n"
."Content-Transfer-Encoding: 7bit\r\n\r\n";
//Insert the plain text message.
$message .= strip_tags($textmessage);
$message .= "\r\n\r\n--PHP-alt-$random_hash\r\n"
."Content-Type: text/html; charset=\"iso-8859-1\"\r\n"
."Content-Transfer-Encoding: 7bit\r\n\r\n";
//Insert the html message.
$message .= $htmlbody;
$message .="\r\n\r\n--PHP-alt-$random_hash--\r\n\r\n";
//include attachment
$message .= "--PHP-mixed-$random_hash\r\n"
."Content-Type: application/pdf; name=$pdf_file_name\r\n"
."Content-Transfer-Encoding: base64\r\n"
."Content-Disposition: attachment\r\n\r\n";
$message .= $attachment;
$message .= "/r/n--PHP-mixed-$random_hash--";
//send the email
$mail_sent = @mail( $to, $subject, $message, $headers );
//if the message is sent successfully print "Mail sent". Otherwise print "Mail failed"
$sent = $mail_sent ? $pdf_file_name . " was sent to " . $_POST['email_to'] . " successfully." : "The invoice was not sent. Please try again.";