在这种情况下，如何格式化我的邮件程序

Question

我希望格式化我的邮件：字体颜色，大小等。所以这里有stackoverflow和我发现的很多地方，必须添加$mail->IsHTML(true);以应用任何内联归因。

由于我的知识不足，我无法理解如何以及在哪里将我的php邮件添加到此行。

这是邮件：

<?
class Mailer
{
  function sendWelcome($user, $email, $pass, $evcode){
     $from = "From: ".EMAIL_FROM_NAME." <".EMAIL_FROM_ADDR.">";
     $subject = "Welcome!";

     if($session->$userlevel == 1){ $emailline = "You need to verify the link below\n"
    .SCRIPT_LOCATION."/mail.php?verify=".$evcode."\n\n";
     } else { $emailline = "\n";}

     $emailline = "Before you can start verify the link \n"
         .SCRIPT_LOCATION."/mail.php?verify=".$evcode."\n\n";
     $body = $user.",\n\n"
         ."Welcome! You've just registered at us "
         ."Username: ".$user."\n"
         ."Password: ".$pass."\n".
     $emailline
         ."N.B.: THIS VERIFICATION VALID ONLY FOR 7 DAYS\n"
         ."Thank you";
    return mail($email,$subject,$body,$from);
  }
};

/* Initialize mailer object */

$mailer = new Mailer;

?>