+=== 0^DIRECTORY NEW^List all new messages
+=== 0^DIRECTORY TO <call>^List all messages to <call>
+=== 0^DIRECTORY FROM <call>^List all messages from <call>
+=== 0^DIRECTORY SUBJECT <string>^List all messages with <string> in subject
+=== 0^DIRECTORY <nn>^List last <nn> messages
+=== 0^DIRECTORY <from>-<to>^List messages <from> message <to> message
+List the messages in the messages directory.