<tr valign="top">
    <th scope="row"><label for="use_api">Use the YMLP API?<br /><small>(recommended)</small></label></th>
    <td><input type="checkbox" id="use_api" name="nsu_mailinglist[use_api]" value="1" <?php if(isset($opts['use_api'])) checked($opts['use_api'], 1); ?> /></td>
</tr>
<tbody class="api_rows"<?php if (!isset($opts['use_api']) || $opts['use_api'] != 1) echo ' style="display:none" '; ?>>
    <tr valign="top">
        <th scope="row">YMLP API Key <a target="_blank" href="http://www.ymlp.com/app/api.php">(?)</a></th>
        <td><input class="widefat" type="text" id="ymlp_api_key" name="nsu_mailinglist[ymlp_api_key]" value="<?php if (isset($opts['ymlp_api_key'])) echo esc_attr($opts['ymlp_api_key']); ?>" /></td>
    </tr>
    <tr valign="top">
        <th scope="row">YMLP Username</th>
        <td><input class="widefat" type="text" id="ymlp_username" name="nsu_mailinglist[ymlp_username]" value="<?php if (isset($opts['ymlp_username'])) echo esc_attr($opts['ymlp_username']); ?>" /></td>
    </tr>
    <tr valign="top"><th scope="row">YMLP GroupID<br /><small>(starts at 1, check URL when 'viewing all contacts' in certain group)</small></th>
        <td><input class="widefat" type="text" id="ymlp_groupid" name="nsu_mailinglist[ymlp_groupid]" value="<?php if (isset($opts['ymlp_groupid'])) echo esc_attr($opts['ymlp_groupid']); ?>" /></td>
    </tr>
</tbody>