Email with subject " IMMI Acknowledgment for documents received"

I got email from DHA on 19th July from a case officer with the heading in subject. I had lodged on 1st March. My understanding is that immi commencement email should mention something about progress. Although it is clear that my application is under process but I am just curious as why I have been sent this letter. did anybody else also got such a letter?

Bro i got the same mail today… when u got ur grant after that mail?

you got grant?