Some of my customers do not need reminding, they simply have a big AP process and reminding is unnecessary, however other customers do need reminding, and at different intervals depending on my past transactions with them. Like "Bob" likes to "forget" and needs to be reminded every 7 days, while "Jim" gets a 15 day 'unspoken' grace period before I start nagging him. And no, simply chaining the due date won't work bc if Jim thinks he doesn't owe it for 15 days, then I won't see it for 30. So at the customer level, I'd like any invoice made for Bob to send a reminder at the 7 day mark, and Jim at 15 days, and so forth, meanwhile leaving my large customers alone.