<?php
declare(strict_types=1);

$recipient = "reader@example.test";
$subject = "Loan receipt";
if (filter_var($recipient,FILTER_VALIDATE_EMAIL) === false || str_contains($subject,"\r") || str_contains($subject,"\n")) throw new InvalidArgumentException("Invalid mail fields");
$queue = [];
$queue[] = ["to"=>$recipient,"subject"=>$subject,"body"=>"Your fictional loan was recorded."];
echo count($queue), " message prepared; none sent\n";