My little dog used to go crazy when anyone would enter or leave my house. He scared guests so much that they would return to their seats until I picked him up and made sure that they were out of harms way. One guest was even bitten! Luckily no blood was drawn!  I needed to teach him to do something else when people left my house. I told him to sit and remain calm and rewarded him with treats. I had a guest walk to the door, if he didn’t bark, I would reward him with a treat. I then had the guest walk back into the living room again, then walk again to the door. If my dog remained quiet, I would give him another treat. Eventually my guest  left. This did help but my dog had to be constantly reminded to sit and be quiet when someone would get up to leave. Eventually he did it on his own. It is not necessary to put your dog in his crate or dog carrier while your guests are visiting.You must persist and your dog will eventually learn. Once he learns, usually  he will never forget.  At least my guests were no longer suggesting that I put my poor little dog in the microwave!!!