Out of the box vTiger comes with few email notifications already enabled. The notifications are triggered when:

• Opportunity is created
• Trouble Ticket has been updated from Customer Portal
• Trouble Ticket has been created from Customer Portal
• New Comment has been added to the Trouble Ticket

These notifications are triggered by vTiger workflow. To turn the notifications off, you would do:

• Mouse over the “gear” icon on the right upper corner
• Click “CRM Settings”
• Under “Other Settings” click “Workflow“
• Click on the Workflow you want to disable
• Scroll down to “Tasks” section and modify the Task
• Once the task opens, set the “Status” to “Inactive” and save the task.