第一次：This is just a friendly reminder that payment on invoice (number), which we sent on (due date), is due today. You can make a payment to the bank account  on the invoice. 另礼貌套话 l  I would be grateful if you could confirm that everything is on track for payment. l  I would be grateful if you could let me know when we canexpect to receive your payment. l  Please let us know about when payment will be made as a matter of urgency. l  Could you reply to this message and let me know you’re received my email? 第二次：Our records show that we haven’t yet received payment on invoice(number), which we sent on (due date) and is overdue by one week. Could you possibly check this out on your end? If the payment has already been sent, please disregard this notice. And if you’re lost the invoice, please let me know, and I’d be happy to send you another copy. 第三次： I emailed you quite a few times to remind you of the pending amount of (payment amount) for invoice(number). As another reminder, payment was due two weeks ago.      If you have any queries 疑问 regarding this payment, please let me know. I’ve also attached a copy of the invoice to this email, in case 万一 the original was lost or deleted.