How can I send outstanding amount details to my customers?

You can follow the below steps to send details related to account balance for a particular customer

1. Click on reports
2. Click on Statement of Account
3. From the drop-down, select the Contact (customer)
4. Once you have selected the customer, click on Email option

This will email the Customer's statement of account which will inform the customer about the pending balance for which he needs to make a payment to you