回複：A dumb question: how to package and mail

I have a EB1 application with 800 pages and I have to use multiple binders.
-It may be too much. You may reduce the size, e.g. only provide the first page of your applications, just select the important evidences, etc. If you provide too much materials, the IO may feel boring nad unhappy.

I'm wondering what is the best way to mail it? I feel weird to mail it to USCIS in a parcel box, but there seems no envelope large and sturdy enough. Thanks for your advice.
-See the left icon in this webpage: "移民局填表 ABC"
文件的準備和遞交 part.