You can easily send group emails in in the Web App from the 'send email' tab. From here you can select clients in the group based on any search criteria you might want to use. Place a check mark next to the clients you wish to send the email to, then click 'next' here you can select or create your own email template (for example 'monthly newsletter') that will be saved for future use, or create a one off email in the email body region. Click 'next' and the group email will go out.