How long is it taking the IRS to open mailed in tax returns?

I filed my tax by mail. It was delivered to the IRS on 3/8/21 (verified by certified mail receipt) - that was 8 weeks ago. I get no status info when I check "Where's MY Refund" on the IRS website - not even a "Return Received" notice  Should I resend a copy of the tax return to the IRS?