Is there an add-on that offers different payment options by customer?
For example, I may want to offer an open account (ie: Net 30 terms) to some customers, but not to all of them. I'd like a way to enable (and disable) this flag in the customer's account (in admin), so that when they place an order, the "open account" payment option is available, but only if this flag is set.
While I'm thinking of it, it would also be nice to have an additional field in the orders table for an optional Purchase Order number.
While this works (sort of), I have found bad email addresses that pass the test. Besides, osC has its own built-in function, tep_validate_email(). So, I would like to revise this to use tep_validate_email(), but I have no idea how to do this. I have looked at other places that use this function ( such as create_account.php and account_edit.php ), but neither of these are boxes or modules. Can someone point me in the right direction?