I do very few face-to-face anymore, since COVID.  I'll meet some clients out in the front office for a quick hello (how ya doing, how are kids/grandkids, yada yada).  The trap door wouldn't work there, but they don't get to sit down so it's easier get them to leave.

Back in the day, I'd had those envelopes back to the client with the comment " do you really want to pay me $$$/hour to open your mail ?  Very few came in with unopened mail again.  Several, I actually put a line item on the invoice "mail opening charge".