Disable all emails to clients

Disable all emails to clients

We do not want Zoho sending emails to clients without our explicit permission. Is there a way to disable all emails? For example, when I associate a project with a client, they get an email even though we have indicated that they should be opted out of all emails. 

Quite frankly, it is infuriating that the system is, essentially, sending spam to people just because we want to be able to track that they are associated with a project.