First remain calm Its a long painful process. Getting extra worked up just makes it worse, be like water and go with the flow. Trust me your going crazy we all do, being a better calmer you is super important right now.
I will tell you what that status really meant for us but it may be something different for you keep that in mind.
we got that document mailed notice which actually meant they had sent us a document that was “returned to sender” (why they dont just say that!!!?….) because my attorney had messed up our street address in the application 1789 instead of 1879. You need to go review the copy of your sent application make sure the address is where you actually live.
if indeed you need to update your address with them thats your next step. Bad news/goodnews now your already delayed, added 6 months for us and we were the last of our cohorts approvals. Good news its nothing bad in terms of if your actually approved in the end.
stay calm, flow like water with the process.