A mailslot is a mechanism for one-way interprocess communications (IPC). A Win32-based application can store messages in a mailslot. The owner of the mailslot can retrieve messages that are stored there. These messages are typically sent over a network to either a specified computer or to all computers in a specified domain. A domain is a group of workstations and servers that share a group name.
You can choose to use named pipes instead of mailslots for interprocess communications. Named pipes are a simple way for two processes to exchange messages. Mailslots, on the other hand, are a simple way for a process to broadcast messages to multiple processes. One important consideration is that mailslots use datagrams, and named pipes do not. A datagram is a small packet of information that the network sends along the wire. Like a radio or television broadcast, a datagram offers no confirmation of receipt; there is no way to guarantee that a datagram has been received. Just as mountains, large buildings, or interfering signals might cause a radio or television signal to get lost, there are things that can prevent a datagram from reaching a particular destination. Named pipes are like telephone calls: you talk only to one party, but you know that the conversation is occurring. For more information about named pipes, see Pipes.