PHP Mailer for Sending Test HTML Emails to Multiple Clients

emailer.php

<?php
$url = "http://example.com/email.html";
if ( $_GET["url"] != "" ) {	$url = $_GET["url"]; }

// Determine Recipients
$recipients = $_GET["to"];
$to = "default.recipient@example.com";

// Desktop Clients
if ($recipients == "mail") { $to = "mail.user@example.com"; } // Apple Mail (Gold Standard)
if ($recipients == "thunderbird") { $to = "thunderbird@mozilla.com"; } // Standard HTML parsing (Golden)
if ($recipients == "outlook-pc") { $to = "outlook.user@microsoftexchange.com"; } // Outlook Desktop PC (Spawn of Satan)
if ($recipients == "outlook-mac") { $to = "outlook.pc@microsoftexchange.com"; } // Outlook for Mac (Tolerable HTML rendering)

// Mobile Clients
if ($recipients == "ios") { $to = "ios.user@example.com"; } // iOS Mail (Gold Standard, again)
if ($recipients == "android") { $to = "android.user@example.com"; } // Android Email (Unknown)
if ($recipients == "gmail-android") { $to = "gmail-android.user@example.com"; } // Gmail on Android (Assuming the worst)
if ($recipients == "gmail-ios") { $to = "gmail-ios.user@example.com"; } // Gmail on Android (Dreadful, real estate thief. Quit messing.)

// Web Clients
if ($recipients == "yahoo") { $to = "nbjacobson@yahoo.com"; } // Yahoo (Problem Child)
if ($recipients == "aol") { $to = "aol.user@aol.com"; } // Aol (Pretty Decent Web client)
if ($recipients == "facebook") { $to = "facebook.user@facebook.com"; } // Facebook (Pretty Good, Lightboxed)
if ($recipients == "outlook") { $to = "outlook.user@outlook.com"; } // (Reasonably compliant Web email client)
if ($recipients == "gmail") { $to = "gmail.user@yahoo.com"; } // Gmail (Problem Child)
if ($recipients == "aol") { $to = "aol.user@aol.com"; } // AOL
if ($recipients == "yahoo") { $to = "yahoo.user@yahoo.com"; } // Yahoo

// Groups
if ($recipients == "group") { $to = "tester1@example.com, tester2@example.com, tester3@example.com"; } // Group

// Get the HTML
$crl = curl_init();
$timeout = 5;
curl_setopt ($crl, CURLOPT_URL,$url);
curl_setopt ($crl, CURLOPT_RETURNTRANSFER, 1);
curl_setopt ($crl, CURLOPT_CONNECTTIMEOUT, $timeout);
$ret = curl_exec($crl);
curl_close($crl);
$html = $ret;			
echo $html;

// Send the Email
$time = date('h:i:s');
$subject = "HTMail ".$time."";
$subject = "HTMail: Happy and Warm ".$time."";
$message = $html;
$from = "email.designer@example.com";
$headers = "MIME-Version: 1.0\r\n";
$headers .= "Content-type: text/html; charset=iso-8859-1\r\n";
$headers .= "From: Email Tester <email.designer@example.com>\r\n";
mail($to,$subject,$message,$headers);
echo "Mail Sent.";
?>