I keep getting a malformed address: error

I keep getting a malformed address: error

**********************************************************
A message that you sent contained one or more recipient addresses that were
incorrectly constructed:

  admin@asite.com <admin@asite.com>: malformed address: <admin@asite.com> may not follow admin@asite.com

This address has been ignored. The other addresses in the message were
syntactically valid and have been passed on for an attempt at delivery.
**************************************************************

Here's the code I'm using:


***************************************************************
<?

// send email
$myname = $contact_name;
$myemail = $contact_email;

$contactname = $signup[fname];
$contactemail = $signup[email];
$message = "Hello ".$signup[fname].",<BR>".
"Get ready to start getting the hits you deserve.  Now here is your login info:<BR><BR>".
"username: ".$signup[username]."<BR>".
"password: ".$signup[password]."<BR><BR>".
"<B>The next step is to click on this link to activate your account: <a href=".$siteUrl."activate.php?username=".$signup[username].">CLICK HERE</a></b>";
$subject = $title;

$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-type: text/html; charset=iso-8859-1\r\n";
$headers .= "From: ".$myname." <".$myemail.">\r\n";
$headers .= "To: ".$contactemail." <".$contactname.">\r\n";
$headers .= "Reply-To: ".$myname." <".$myemail.">\r\n";
$headers .= "X-Priority: 1\r\n";
$headers .= "X-MSMail-Priority: High\r\n";
$headers .= "X-Mailer: Just My Server";

mail($contactemail, $subject, $message, $headers);
$signup[username] = "";
?>

***************************************************************

I have just changed to a new server.  
This code worked fine on the my last server with no errors.