Kenny Zaron

This plugin allows for network administrators on WordPress multisite environments to send an email to users that 
they select based on the users’ roles in individual sites. For example, checking only “editors” will go through 
each active site and add anyone with the role of “editor” to your list of emails to send to.
To use the plugin after installation & activation, find Users / Mass Email in the network admin dashboard in your 
multisite install. Then, select the user types you wish to email and click on the button for “Load the List”. This 
will load the list of users to email. Then you may compose your email in the boxes provided and click the send 
button at the bottom of the screen. If all goes well you will be presented with a confirmation page indicating 
that your email was sent successfully.
This plugin is NOT intended for administrators to be sending unsolicited spam to their users. In fact, it was 
created with more formal environments in mind. One example would be a University setting where administrators 
of the network may need to notify students and faculty of potential downtime. With the plugin’s implementation 
I would imagine it would be a highly inefficient way of sending spam anyway.

Network Mass Email

Allows network admins to send a manually created notification email to all registered users based on user role.

Meitar

Multisite Directory provides a customizable Network-wide site directory for WordPress Multisite installations. You can categorize subsites in your Network, add full-length descriptions and featured images to them, and more. Theme developers can customize the look and feel of the site directory using all the tools they’re already familiar with. Blog authors can use a highly-configurable shortcode (<code>[site-directory]</code>) to display the directory anywhere shortcodes are supported.
Each time a new site or blog is added to your Network, a corresponding entry in the site directory is added, too. The directory is managed from the Network’s main site, but most changes to the subsites (other blogs) automatically update the directory. Many parts of a given site’s appearance in the directory can be modified without affecting the site itself. This means a Super Admin can use a custom site logo, tagline, and so on in the directory itself, without changing the site’s actual logo, tagline, and so on. Additional options in the Network Settings → Network Directory section allows Super Admins to tweak the bells and whisltes, such as keeping Directory Entry titles in sync with Site Name changes.
Site directory entries are implemented as a hierarchical custom post type in the main site. These pages can be categorized with a custom <code>subsite_category</code> taxonomy. We’ve found that this combination allows maximum flexibility while providing the tightest integration with existing WordPress core features. As a result, no new tables are added to your install, and no side effects are introduced. It Just Works.(TM)
Quickstart guide
After <a href="https://wordpress.org/plugins/multisite-directory/installation/" rel="ugc">installing</a> the plugin, you’ll want to:
<ol>
<li>As a Super Admin, go to My Sites → Network Admin → Sites. Notice the new “Categories” link on the sidebar.</li>
<li>Create some categories! If the category relates to a location (maybe it’s a site for a regional chapter of your organization?), be sure to click the map to geotag it.</li>
<li>Click on “Directory,” immediately above “Categories.” These pages are the individual directory entries, not the blogs. Categorize these pages as you would regular WordPress Pages to organize your Site Directory.</li>
<li>Go to any site’s Appearance → Widgets screen, and add a “Network Directory Widget” to a widget area.</li>
<li>If you’ve geotagged some of your Site Categories, choose “Display as map” from the widget options. (Otherwise, leave it on “Display as list.”)</li>
<li>Click Save, view your blog, and enjoy your new Site Directory!</li>
</ol>
Check out the <a href="https://wordpress.org/plugins/multisite-directory/screenshots/" rel="ugc">Screenshots</a> for a few examples. 
This plugin provides a number of functions to Theme authors so that they can make use of the Multisite Network Directory features in their themes. This section documents those functions. For implementation details, see this plugin’s <code>includes/functions.php</code> file.
<h4>get_site_directory_terms</h4>
Gets all categories in the site directory.
<ul>
<li>@return array|false|WP_Error</li>
</ul>
<h4>Get site terms</h4>
Gets the categories assigned to a given blog in the network directory.
<ul>
<li>@param int $blog_id</li>
<li>@return array|false|WP_Error</li>
</ul>
<h4>the_site_directory_logo</h4>
Prints the site’s custom logo or the site directory entry’s featured image, if it has one.
<ul>
<li>@param int $blog_id Optional. The ID of the site whose logo to get. Default is the current directory entry’s site’s logo.</li>
<li>@param string|int[] $size</li>
<li>@param string|string[] $attr</li>
<li>@return void</li>
</ul>

Multisite Directory

Add a browseable, flexible directory of the sites in a WP Multisite network. Each subsite gets its own page.

Network Mass Email vs Multisite Directory