PHP Mail函数发错时间错误?

I am using the following code to send a message. The current time is 9:20 PM on my phone, on the server, and on my Mac. I execute this code and I receive and email on my phone. But it says that it got it at 9:23.. Three minutes into the future... How is this happening

$to  = 'me@domain.org' . ', '; // note the comma
$headers  = 'MIME-Version: 1.0' . "
";
$headers .= 'Content-type: text/html; charset=iso-8859-1' . "
";
$headers .= 'From: Check-in Report <reports@fsbcheck.in>' . "
";

// Mail it
mail($to, $subject, $message, $headers);

That timestamp (9:23) is set when the SMTP server reports sending it. Wherever your outgoing mail server is, the system clock on that machine needs adjusting.