use garethpewsAPIType;
use garethpewsMailAPI;

$api = MailAPI::withUsernameAndPassword("host", "username", "password");
$message = new TypeMessageType();
$message->setSubject("Some Subject");
$message->setBody("Test Email");
$message->setToRecipients("test@test.com");
$message->setReplyTo("me@there.com");
$api->sendMail($message);

'replyTo' => NULL,