I forgot to attach the file in my previous e-mail.
我忘记在上一封邮件里添加附件了。
I forgot to attach the file in my previous e-mail. Here you go.
我忘记在上一封邮件里添加附件了。因此再给你发一次。

Delete the file immediately.
看完后请立即删除该文件。
Download the file and save it as whatever you want.
请下载该文件，保存时可自行设定文件名。
Do not delete this e-mail.
请不要删除此邮件。