Get current user array into hyperlink

I would set up an array with the variables you want in the url query string and then use http_build_query().

Like so:

$args = array( 'AT' => 'EN',
               'AE' => $current_user->user_email,
               'FN' => $current_user->user_firstname,
               'LN' => $current_user->user_lastname,
               'MK' => 665080128,
               'PW' => 'miami',
               'BU' => 'http://thinkmcat.com/');

?>

<a href="https://thinkmcat.webex.com/thinkmcat/m.php?<?php echo http_build_query($args); ?>">LINK</a>