Send email with attachments from folder on web server

<?php


use PHPMailer\PHPMailer\PHPMailer;
use PHPMailer\PHPMailer\Exception;
use setasign\Fpdi\Fpdi;

require 'PHPMailer/src/Exception.php';
require 'PHPMailer/src/PHPMailer.php';
require 'PHPMailer/src/SMTP.php';

//configure database access
	$dbuser = 'user';
	$dbpass = 'pass';
	$database = 'database';
	$dbserver = 'servername';
	$db = mysqli_connect($dbserver, $dbuser, $dbpass, $database)
	or die ('Database not available');

if(!isset($_POST['submitted'])){
	//display form if not submitted
	print "<p><strong>Press submit to send letters</p>";
	?>
	<form name="" action="test.php" method="POST">
		<input name="submitted" type="hidden" value="submitted">
		<input name="submit" type="submit" value="Post Letters">
	</form>
	<?php
}else{
	$dir = "letters";
	if (is_dir($dir)){
	  if ($dh = opendir($dir)){
		while (($file = readdir($dh)) !== false){
			if (strstr($file,".pdf")){
				$number++;
				$letter1 = "letters/".substr($file,0,8).".pdf";
				$letter2 = "letters/".substr($file,0,8)."-2.pdf";
				if(strstr($file,"-2.pdf")){
				
				}else{
					sendMail($db,$letter1,$letter2);
				}
	
			} 
		}
		closedir($dh);
	  }
	}else{
		echo "No directory found";
	}
}


function sendMail($db,$letter1,$letter2){

	$personid = substr($letter1,8,8);
	
	$query = "SELECT person_id, forename, surname, email_address FROM people_table WHERE person_id = ".$personid;
	
	$result = mysqli_query($db,$query) or die (mysqli_error()."<br> Query error");
			while($row = mysqli_fetch_array($result)){
				$sforename = $row['forename'];
				$ssurname = $row['surname'];
				$emailaddress = $row['email_address'];
			}
	
	$bodytext = "
		<p>
		Dear ".$sforename." ".$ssurname.",
		</p>
		<p>
			HTML Formatted email with attachments
		</p>
	    Best wishes,<br><br>		
		";
	

	$email = new PHPMailer();
	$email->IsHTML(true);
	$email->From      = 'admin@business.com';
	$email->FromName  = 'Admin Office';
	$email->Subject   = 'Important Letter for: '.$personid;
	$email->Body      = $bodytext;
	$email->AddAddress = $emailaddress;
	
	if(file_exists($letter2)){
		
		$email->AddAttachment( $letter2 , $personid."-letter2.pdf" );
		$email->AddAttachment( $letter1, $personid."-letter1.pdf" );

	}else{
	
		$email->AddAttachment( $letter1, $personid."-letter1.pdf" );
	}
	
	return $email->Send();
}

?>