There is now an option to set a send from email address for all broadcast emails, text messages, and notifications. Go to the admin area > settings tab > edit website settings link. In the edit website settings form, enter an email address to send all notifications from in the Set Broadcast From Email Address field.

IMPORTANT: The Set Broadcast From Email Address must be an email address in your own domain name (@yourdomain.com). It cannot be an email address from a different domain or a free email account like @gmail.com or @yahoo.com. Also, DO NOT use info@yourdomain.com. The info@ email address is often filtered out as spam by some email providers.