By default:

• As an organizer, each time you create an email announcement, this is sent to all selected recipients. 
• Additionally, each time a text announcement is sent, you have the option to send that message as an email to members who do not have a cell number on file. 
• Each time a member replies publicly to an announcement, members will receive a daily digest email of all comments. 

There are other options available, and members control their email settings individually.