php mail with PDF attachment header causes to go into just mail - email

Question

I have a webform that generates a PDF which is emailed to me upon submission but the email keeps getting filtered to the spam for folder. I suspect that the something is wrong in the email header but not sure what it could be.
Any help is appreciated.
The following is a snippet...
// send by email
$fileatt = '../pdfs/'.$filename;
$fileatt_type = mime_content_type_manual($fileatt); // File Type "application/pdf"
$fileatt_name = $filename; // Filename that will be used for the file as the attachment
$email_from = "auth#mysite.com"; // Who the email is from
$email_subject = "Auth Report"; // The Subject of the email
//$email_to = "info#mysite.com";
$email_to = "info#mysite.com";
$headers = "From: ".$email_from;
$file = fopen($fileatt,'rb');
$data = fread($file,filesize($fileatt));
fclose($file);
$semi_rand = md5(time());
$mime_boundary = "==Multipart_Boundary_x{$semi_rand}x";
$headers .= "\nMIME-Version: 1.0\n" .
"Content-Type: multipart/mixed;\n" .
" boundary=\"{$mime_boundary}\"";
$email_message .= "This is a multi-part message in MIME format.\n\n" .
"--{$mime_boundary}\n" .
"Content-Type:text/html; charset=\"iso-8859-1\"\n" .
"Content-Transfer-Encoding: 7bit\n\n" .
$email_message .= "\n\n";
$data = chunk_split(base64_encode($data));
$email_message .= "--{$mime_boundary}\n" .
"Content-Type: {$fileatt_type};\n" .
" name=\"{$fileatt_name}\"\n" .
"Content-Transfer-Encoding: base64\n\n" .
$data .= "\n\n" .
"--{$mime_boundary}--\n";

Answer 1

If you add the sender of the email, which is auth#mysite.com for your case, as a new contact to the address book of your email client, then the email won't probably be marked as spam as it comes from a member of your contact address book.