You can specify which notifications a Client receives via People > Clients > select the Client > Edit Profile, using the checkboxes under 'Received Notifications'. The notifications are:
Broadcasts: The Client will receive manual marketing communications via Broadcasts. Be aware that they can unsubscribe themselves from this.
Lesson Reminders: The Client will receive a reminder prior to a Lesson taking place. The amount of notice given is specified in your Lesson Reminders.
Low Balance Reminders: The Client will receive email or SMS reminders when their Balance dips below a certain threshold. You set the threshold via System > Settings > Accounting > Client Balances.
Invoice Reminders: The Client will receive automatic reminders via email or SMS for unpaid Invoices. The time that passes between the Invoice being raised and the reminder being sent is set via System > Settings > Accounting > General.
Credit Request Reminders: The Client will receive automatic reminders via email or SMS for unpaid Credit Requests. The time that passes between the Credit Request being raised and the reminder being sent is set via System > Settings > Accounting > General.
Invoice Payment Requests: The Client will receive payment request emails for Invoices.
Credit Request Payment Requests: The Client will receive payment request emails for Credit Requests.
Welcome emails for Clients
By default, Clients created with the 'Prospect (Pipeline)' status will receive a welcome email. You can change this by unticking 'Send Pipeline Clients a Welcome Email' via System > Settings > Company Details > Branch Details, which will mean that only 'Live' Clients are sent a welcome email.
The Received Notifications checkboxes on a Client's profile.