Is there a way to send a group notification to your clients?

Hello fellow sitters: Does anyone know of a way to send a group email (or notification) to all of your clients, while still keeping their identities private? I would like to offer discounts on certain services during certain months. For example: "Walking Wednesdays"....1/2 off all walks on Wednesdays in the month of May for repeat clients. Maybe a group text via their Rover number? I would like to reach everyone with ONE message, if possible. Thanks!