 pid as part of the
 message contents. The sender can determine his own pid by calling
 <a href="../../../../com/ericsson/otp/erlang/OtpMbox.html#self--"><code>self()</code></a>.
 </p>

 <p>
 Mailboxes can be named, either at creation or later. Messages can be sent to
 named mailboxes and named Erlang processes without knowing the
 <a href="../../../../com/ericsson/otp/erlang/OtpErlangPid.html" title="class in com.ericsson.otp.erlang"><code>pid</code></a> that identifies the mailbox. This is neccessary in
 