Problem with character encoding on email sent via PHP?

Having some trouble sending properly formatted HTML e-mail from a PHP script. I am running PHP 5.3.0 and Apache 2.2.11 on Windows XP Professional.

The output looks like this:

Agent Summary for Support on Tuesday April 20 2010=20 Ext. Name Time Volume
137 Agent Name 01:27:25 1
138 =09 00:00:00 0
139 =09 00:00:00 0

You see the =20 and =09 in there? If you look at the HTML you also see = signs being turned into =3D. I figure this is a character encoding issue as I read the following at Wikipedia:

ISO-8859-1 and Windows-1252 confusion

It is very common to mislabel text data with the charset label ISO-8859-1, even though the data is really Windows-1252 encoded. In Windows-1252, codes between 0x80 and 0x9F are used for letters and punctuation, whereas they are control codes in ISO-8859-1. Many web browsers and e-mail clients will interpret ISO-8859-1 control codes as Windows-1252 characters in order to accommodate such mislabeling but it is not standard behaviour and care should be taken to avoid generating these characters in ISO-8859-1 labeled content.

This looks like the problem but I don't know how to fix. My code looks like this:

ob_start();
report_queue_summary($yesterday,$yesterday,$first_extension,$last_extension,$queue);
$body_report = ob_get_contents();
ob_end_clean();
$body_footer = "This is an automatically generated e-mail.";
$message = new Mail_mime();
$html = $body_header.$body_report.$body_footer;
$message->setHTMLBody($html);
$body = $message->get();
$extraheaders = array("From"=>"***redacted***","To"=>$recipient, "Subject"=>"Agent Summary for $yesterday [$queue]", "Content-type"=>"text/html; charset=iso-8859-1");
$headers = $message->headers($extraheaders);

# setup e-mail;
$host = "*********";
$port = "26";
$username = "*****";
$password = "*****";

# Send e-mail
$smtp = Mail::factory('smtp',
  array ('host' => $host,
    'port' => $port,
    'auth' => true,
    'username' => $username,
    'password' => $password));

$mail = $smtp->send($recipient, $extraheaders, $body);

if (PEAR::isError($mail)) {
  echo("" . $mail->getMessage() . "");
 } else {
  echo("Message successfully sent!");
 } 

Is the problem that I'm using output buffering?