Mail Slot Mailboxes: Secure & Convenient Solutions

I think the introductions to each mechanism on MSDN answers this: Mailslots: A mailslot is a mechanism for one-way interprocess

Metal Rustproof Post Box Wall-Mounted Key Locking Premium Mailbox with Top-Loading Letter Slot Drop Box Case 4 sold 5 Wall Mount Milk Box with Lock

4090 2 slot This 4C versatile™ mailbox from US Mail Supply holds four oversized tenant slots, perfect for an apartment, office building, or campus dormitory Easily mounted

4x8 slot car layouts Anodized Some units also come with a standard outgoing mail slot Other choices