iously. Unique
 identifiers persist across sessions. This permits a client to
 resynchronize its state from a previous session with the server. <p>

 Associated with every mailbox is a unique identifier validity value.
 If unique identifiers from an earlier session fail to persist to
 this session, the unique identifier validity value
 <strong>must</strong> be greater than the one used in the earlier
 session. <p>

 Refer to <A HREF="http://www.ietf.org/rfc/rfc2060.txt">RFC 2060</A>
 for more information.

