USCIS does send card via priority mail with - 回複：緊急求助：卡寄丟了怎麽辦？

USCIS does send card via priority mail with delivery confirmation. - Online Status

When you check DC online, to what zip the mail was delivered, your current address or previous address?
If you're not currently in the US, is there anyone watching your mail so you are sure 現在還沒收到?