this seams to be a bug that was reported on the Pear site with the Mail object on PHP 5 and having the strict error reporting level enabled
bug.php?id=9950
bug.php?id=18254
the email still sends though right?
to suppress the error till the Pear team can correct the problem, change line 190 of the PEAR_Mail_using_SMTP_php.php file:
$theMailer =& Mail::factory('smtp', $paramArray);
to:
@$theMailer =& Mail::factory('smtp', $paramArray);