Open the mailbox and log in to the mailbox home page. Find the button to write a letter or email on the mailbox home page, and then click it. Fill in the recipient and subject in the new page that opens. Enter the information to be sent in the text input box below. If you want to send a file, click the "Add Attachment" button. Select the file to send in the pop-up open dialog box, and click the open button. Wait until you see the prompt of successful upload. Click the Send button below the text box. Then you can see the page prompt that sent successfully.