Sending mass emails to your users will require customization which you may consult your personal developer to achieve on your site. However, you can use a third-party plugin called Mass Email to Users. 

Mass Email To Users is the plugin for sending a mass email to WordPress users. Admin can send an email to WordPress users together. Simple and mass mailer plugin. Admin can have option pagination in the list of all users. Admin can send HTML emails to selected users. Visit this link to learn more:

https://wordpress.org/plugins/mass-email-to-users/

Please note that as it is a third-party plugin, we cannot guarantee support and compatibility as we have not fully tested it, but you are free to try it.

The WordPress repository contains plugins that are considered third-party and some have integration with BuddyBoss. For a complete list of plugins that are integrated with BuddyBoss, you may search our Integrations page: 

https://www.buddyboss.com/integrations/