Requirement
We need to send Email notification to the customer, when the status of an order changes from Pending Fulfilment to Pending Billing
Solution
In NetSuite there is a standard way to send Item fulfilment Emails. For that we need enable the Send Order Fulfilled Confirmation Emails feature. When this feature is enabled, we can send emails to the customer when a fulfillment record is created for a sales order.
Go to SetUp -> Accounting -> Accounting Preferences

Select Order Management tab

Under Fulfilment tab, Check Send Order Fulfilled Confirmation Emails and save.

The email will be auto sent to the customer email id defined in the sales order “To Be emailed” Text field. The standard email will be sent once the Item fulfillment record is saved and it will not look for any other parameter.