Formalization of a well-defined synchronization mechanism can be used to prove that concurrently running processes of a system communicate correctly. This is demonstrated for a system consisting of many sending processes which deposit messages in a buffer and many receiving processes which remove messages from that buffer. The formal description of the synchronization mechanism makes it very easy to prove that the buffer will neither overflow nor underflow, that senders and receivers will never operate on the same message frame in the buffer nor will they run into a deadlock.