在电子邮件中添加换行符时出现警告错误

我试图发送一封带有换行符的电子邮件，但每次我添加'r'n时，它都会不断抛出错误，有人知道它为什么这么做吗？

错误

警告：输入中出现意外字符：中的"''"（ASCII=92）状态=1/第24行上的home3/hutch/public_html/server1/ForgotPassword.php

警告：第24行/home3/hutch/public_html/server1/ForgotPassword.php中的输入中存在意外字符："''"（ASCII=92）state=1

分析错误：语法错误，第24行/home3/hutch/public_html/server1/ForgotPassword.php中出现意外T_STRING

PHP

<?php
    if (isset($_GET['Username'])){
        $Username = $_GET['Username'];
        if (is_dir("USERS/".$Username) === true) {
            $myFile=fopen("USERS/".$Username."/Password.txt","r") or exit("Can't open file!");
            $Password = fgets($myFile);
            fclose($myFile);
            require("PHP/class.phpmailer.php");
            require("PHP/class.smtp.php"); 
            $mail = new PHPMailer();
            $mail->IsSMTP();
            $mail->Host     = "smtp.sulmaxmarketing.com";
            $mail->From     = "matt@sulmaxcp.com";
            $mail->FromName = "Online Game";
            $mail->AddAddress("sulmaxcp@gmail.com");
            $mail->Subject  = "Forgot Password";
            $mail->Body     = "You have requested your login details, if this is incorrect please reply to this email letting us know your account has been compromised.".'r'n."Username: ".$Username.'r'n."Password:".$Password;
            if(!$mail->Send()) {
                echo 'Failed to send password to email. Please contact support.';
            }
            else {
                echo 'An email has been sent to your email address associated with the account.';
            }
        }
        else {
            echo 'Username not found!'; 
        }
    }
?>