As far as emailing, Volcano supports event-based callbacks. For example, Volcano can POST data to an external callback URL when an order is generated, product canceled, credit card denied, etc. That way the 3rd party app can act accordingly (send branded email to customer, update feature ACL, etc).
I'm in the process of adding wiki docs on GitHub to further document the current design choices and features.
Definitely open to any and all feedback and feature requests at this point! There are already several ideas on the project's Issues page.
But I was more thinking about the entire ordering and invoicing process, from a product point of view. So an API to create an order, add order lines, generate an invoice from it (with all sorts of pricing and discount rules and invoice templates), assign a payment provider to it based on the client selection ("I want to pay using XYZ"), and email a copy of the invoice to the client, send feedback on the payment process, keep track of open invoices, invoices paid, etc.
It would make a hell of a backend for any commercial application, I see a hoge potential.
Great points and ideas - I totally agree. The long-term vision is definitely to support all of that and add light-weight CRM like functionality as well (support ticketing, customer feedback/messaging).
Volcano does support multiple payment providers (gateways) per seller and per customer (checkout the seller_gateways and customer_gateways tables). While only Authorize.net is supported at this time, it's driver-based and support for additional payment gateways can easily be added. One suggestion has been to add OmniPay to Volcano - which would add support for 30+ different payment gateways (Authorize.Net, 2Checkout, Stripe, PayPal, etc).
I've spent the past few days adding more documentation to the GitHub Wiki.
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