 processes or
 other instances of this class.
 </p>

 <p>
 Each mailbox is associated with a unique <a href="../../../../com/ericsson/otp/erlang/OtpErlangPid.html" title="class in com.ericsson.otp.erlang"><code>pid</code></a> that
 contains information necessary for delivery of messages. When sending
 messages to named processes or mailboxes, the sender pid is made available to
 the recipient of the message. When sending messages to other mailboxes, the
 recipient can only respond if the sender includes the