在《公约》中，关于发盘的失效问题规定:“一项发盘，即使是不可撤销的，于拒绝通知送达发盘人时终止。”即当受盘人不接受发盘内容，并将拒绝的通知送到发盘人手中时，原发盘失去效力，发盘人不再受其约束。
另外，还有几种情况可以造成发盘失效:①发盘人在受盘人接受之前撤销该发盘;②发盘中规定的有效期届满;
③其他方面的问题造成发盘失效。这包括政府发布禁令或限制措施造成发盘失效。另外还包括发盘人死亡，法人破产等特殊情况。电子通信方式下，发盘的失效的概念与上述相同。
电子信函(邮件)发盘举例
September 10,2015
OFFER
Dear Mr. Johnson,
We are glad to receive your inquiry of September 9#. You will be pleased to note that we have had a long history for over twenty years in handling locks. Our products are popularly received in the European market. As requested, we are making you an offer below:
1.Commodity: Swallow Brand copper locks
2.Packing: Every 100 locks in one carton
3.Quantity, Specification and Price:
10,000 locks, No.2015-F1, US$28.80 per lock FOB Tianjin
4. Payment: by irrevocable L/C at sight to be opened in our favor
5.Shipment: within 30 days after receipt of L/C
Our bank is the Bank of China, you may refer its branch in London to our standing. We look forward to receiving your first order.
This offer is good for five days.
Faithfully,
Feng Zhang
