+#define IMAP4_CMD_CAPABILITY "CAPABILITY"
+#define IMAP4_CMD_LOGIN "LOGIN"
+#define IMAP4_CMD_SELECT "SELECT"
+#define IMAP4_CMD_EXAMINE "EXAMINE"
+#define IMAP4_CMD_LOGOUT "LOGOUT"
+#define IMAP4_CMD_SEARCH_UNSEEN "SEARCH UNSEEN"
+
+/* Responses from IMAP4 server. */
+#define IMAP4_RSP_SUCCESS "OK"
+#define IMAP4_RSP_FAILURE "NO"
+#define IMAP4_RSP_PROTOCOL_ERR "BAD"
+#define IMAP4_RSP_SEARCH_UNSEEN "* SEARCH " /* This is the line that will be returned by
+ * the IMAP4 server after receiving the
+ * "SEARCH UNSEEN" command, followed by the
+ * messages ID of the unseen messages. */