Hi Mark,
If you are a .NET developer (or have access to one), automating the creation of a recurring invoice is as easy as calling a couple stored procedures. I have a document describing the calls you need to make to accomplish this.
Then each month, as long as the client has a valid credit card on file the invoice will be generated and immediately charged to that card, and the client will receive an email thanking them for payment (you could disable this).
The initial payment of the first invoice could be tricky; having the client log in and pay it manually would be one option. Another would be to use the Payment object within the DotNetInvoice code to post a payment, and then save their credit card info into the DB (using a stored procedure). There is code in the app that does this, but it's triggered from a web page. You could easily make these same calls from your code. Either way will ensure future generated invoices are paid immediately.
One other note - this recurring charge stuff only works with Authorize.NET. PayPal Website Payments Pro doesn't support it because they require CVV code, and per the Visa agreement we cannot store CVV in the application.
Let us know if you have any other questions,
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Rob
DotNetInvoice Support