Volume Limits of Print Receivables Transactions - Email 100k Invoices per day?

OTC is an online retailer with daily sales volumes ranging from 20k-100k orders per day.

Right now we are only using Print Receivables Transactions for customers with a balance, generally our 'terms' customers. That's something like 10% of order volume.

We are considering using this program to send invoices (with $0 due) to all customers which could mean 20k-100k emails issued via Print Receivables Transactions.

The Import Auto Invoice is already handling this volume but we flag them not to print when balance is $0.

Anyone else doing this kind of volume in AR? Anyone else with this volume emailing invoices or other docs?