How do I request a deposit for an existing invoice that has been emailed.
You might want to reach out to your client, Mntvista.
Also, you can add a note on the Customer message box for your payment conditions.
Mention me if you need anything else.
An invoice is a final sale, typically you get a deposit first, then do the work, then invoice
Since you have entered the invoice, and sales income is posted, call the customer and ask for a partial payment (deposit). if you invoice for a deposit, income will be higher than it should be