Why did the upload fail and the information was lost by sending letters and attachments with Netease mailbox?

The upload failure may be caused by temporary network interruption, manual cancellation or name conflict. You can do it. If it fails, cancel it and add it again. If your attachment is too large (several meters in space), it is suggested that you send it separately, so as to avoid receiving your mail normally due to insufficient capacity of the other party's mailbox, which is also a way to avoid network interruption.

If you still can't submit it again, you can copy the contents of the backup email body first, and then go back and create a new email sending test.