Source: templates/loop-message.php

<?php
/**
 * The Template for outputting Message Archive items
 *
 * Override this template by copying it to yourtheme/sensei/loop-message.php
 *
 * @author      Automattic
 * @package     Sensei
 * @category    Templates
 * @version     1.9.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * This runs before the the message loop items in the loop-message.php template.
 * It runs only only for the message post type.
 * This loop will not run if the current wp_query has no posts.
 *
 * @since 1.9.0
 *
 * @hook sensei_loop_message_before
 */
do_action( 'sensei_loop_message_before' );
?>

<div class="message-container" >

	<?php
	/**
	 * This runs before the post type items in the loop.php template.
	 * It runs within the message loop <ul> tag.
	 *
	 * @since 1.9.0
	 *
	 * @hook sensei_loop_message_inside_before
	 */
	do_action( 'sensei_loop_message_inside_before' );
	?>

	<?php
	// loop through all messages
	while ( have_posts() ) {
		the_post();

		sensei_load_template_part( 'content', 'message' );

	}
	?>

	<?php
	/**
	 * This runs after the post type items in the loop.php template.
	 * It runs only for the specified post type
	 *
	 * @since 1.9.0
	 *
	 * @hook sensei_loop_message_inside_after
	 */
	do_action( 'sensei_loop_message_inside_after' );
	?>

</div>

<?php
/**
 * This runs after the post type items in the loop.php template.
 * It runs only for the specified post type
 *
 * @since 1.9.0
 *
 * @hook sensei_loop_message_after
 */
do_action( 'sensei_loop_message_after' );
?>