因为延迟交货3周写一封英文电子邮件投诉：1 感谢电子邮件的发件人2 道歉3 解释延误的原因4 采取行动5提供补偿6 再次道歉

Subject: Complaint about delayed delivery

Dear [Name of the email recipient],

First of all, I would like to express my gratitude for your email and for bringing to our attention the delayed delivery of our order. We apologize for the inconvenience this has caused you and your company.

We understand that the delayed delivery of our order has caused a lot of inconvenience and frustration. We would like to explain the reason for the delay. Unfortunately, we encountered some unexpected issues in our production process that caused us to fall behind schedule. We understand that this does not excuse the delay and we are taking steps to prevent this from happening in the future.

In order to rectify the situation, we have taken immediate action to expedite the delivery of your order. We have also put in place measures to ensure that such delays do not occur in the future.

We understand that time is of the essence and we would like to offer you a discount on your next order as compensation for the delay. We value our customers and we want to make sure that we provide you with the best service possible.

Once again, we apologize for the delay and any inconvenience it may have caused you. We appreciate your understanding and look forward to continuing our business relationship with you.

Sincerely,

[Your Name