Usually, you can find it in the following steps:

1. Log in to your AliExpress Seller Center account

2. Click "My Orders" or "Sold Products" or "Evaluation Management" or "Customer Management" in the left navigation menu;

3. Find the specified order or customer, and click "Details" or "Contact Buyer";

4. After entering the order or customer details page, select "Send Email" or "Send Message" as needed, write the email content and send it.

The specific operations may be slightly different and can be adjusted appropriately according to the actual situation.