No update on receipt of passport

[Pp.chn]

We got an email requesting to send our passports for the Canada visitor Visa on 26th Feb. We sent it and got a confirmation from the courier service that it is delivered. But we have not got a status update on the official website. How do we know if the passport has been received by them? When can we expect to get the passport back? We are currently in the US.

Thanks in advance for your help!!