What do you do when you delete the mailbox?

I think once you delete the mail box you can't get it back.

Hehe, I've had the same thing happen to me and I think the things I tried and had success with most, some were just claims from friends, were:
A: Move out. i.If you like your house, move your Sim out, add your Sims house to the House Bin, and place the house in the place of your desire. Then there will be multiple versions of your house in the bin. I believe my friend tried it and it worked for her, but I haven't confirmed it.
ii. If you want to move out, or if you're willing to, then move out and choose a different house (if you don't have the money to buy the perferred house, open the cheat code (Ctrl+Shift+C) entry box, and enter motherlode multiple times. You will then recieve 50,000 simeleons.

B: Don't save after you've done this action. Then again, if exit the game and come back, I believe the mail box is there. C: Every time the Repo Man comes, pause, open the Cheat Code Menu (Ctrl+Shift+C), enter boolprop testingcheatsenabled true, Shift+click the Repo Man, choose the Force Error option, and when the pop- up comes up, hit the Delete option. If he doesn't come out of his car after you delete him, keep the car there, so that way he won't have a place to pull into. If he does come out of the car, delete him again and his car as well. (If you have an emergency while his car is still present-such as a fire or a burglar-use the cheat code mentioned above and Shift+click the burglar, force error, and hit delete. For the fire, cancel the Fire! action for all Sims, evacuate them, Shift+click the flame(s), and there should be an Extinguish option in the menu. If not, Force Error and delete. It may delete your stove or fireplace (or whatever the source of the fire), so you'd have to replace it if you wanted.

Sometimes I wish there were no Repo Man, but then there would be a missing point in the game; it's a game of life, and you have to pay for most of the stuff he takes.

I was alwasy afraid of that..you can always delete the repo..I don't know if that would work.

Replacing mailbox and trash can with SimPE:

There might be a more direct way to do this, but this one works.

Once SimPE loads, click "finder" at the bottom of the page. In the box labeled "Match", enter "mailbox" or "trash can" and click "start". In the results area, double-click "mailbox" (or trashcan). Then, click "plug-in view" at the bottom of the page. You should be looking at the Object Data Editor. The only thing you want to do here, in the Catalog Sort area, is decide where you want the item to appear in the Buy Mode. You can follow those steps for the item that you didn't choose, or you can go to the Resource List at the top of the page and select that item. If you choose the latter, make sure that you select "mailbox" with the folder icon and "trash can - outside". Don't forget to click "commit" and, from the "file" menu, "save", in that order, before you exit SimPE.

Easiest thing to do is go to edit town and move your house to a new lot!!! That's it!!! All your stuff will move with you