I have this bug going on. I can't get elements, or anything else, in the mail in my current save. Somehow my mailbox has gotten broken. I'm almost sure it started when I completed the decorative egg collection. Before that, I'd been able to get a postcard and my bills in the mail. When I completed the collection, I got a popup saying that a bunny was coming by to deliver something special, but I never saw a delivery and never got any mail. My sim did not get any mail after that. No bills, no postcards, and no geo council items.
I tried to reset the mailbox with testing cheats, which made the bills arrive, but the "get mail" option was greyed out when it shouldn't be. I was able to pay the bills, but still can't receive any items. This is in a save started after patching. I tried clearing and repairing the install of the game, but that did not fix the problem. I did not factory reset. I do have mods, but being that I've seen people posting about this issue who have no mods, I don't think they're the problem, and none of them are on the list of mods broken by the patch over at Mod the Sims.
Also, I never did get the stuffed bunny reward! I can buy it from buy mode, but I'm thinking the reward one I got is somehow broken or bugged and that's why the mailbox no longer works.