You must have established both a QuickBooks Online and Deluxe eChecks account.
How it works
At a high level, the first step is to link your QuickBooks Online bank accounts to your eChecks checking accounts quickly and easily with the FREE Deluxe eChecks QuickBooks Online add-on. The one-time set up requires less than 5 minutes. Once connected, simply add email addresses to any vendors in QuickBooks Online you want to pay with eChecks. All QuickBooks Online users with access to pay bills and create checks will then be able to create and send eChecks.