mail::account::folderFromString — Restore a folder object
        #include <libmail/mail.H>
        mail::account *account;
        mail::folder *folder;
        
        std::string savedFolder=folder->toString();
        
        ...
| mail::folder *f=account->folderFromString( | std::string savedFolder ); | 
savedFolder is a
      folder object that was previously saved as a string. The
      mail::account::folderFromString
      method recreates the original folder object. That is, the
      returned mail::folder object
      refers to the same mail folder as the original mail::folder object.
Folders may only be recreated by mail::account objects that reference the same mail account referenced by the original mail::folder object.
This function returns a NULL pointer if it cannot allocate memory for the new mail::folder object.
mail::folders are linked to their corresponding mail::accounts. A mail::folder created by one mail::account may not be used with a different mail::folder. All mail::folders created by a mail::account are invalidated when this mail::account object is destroyed. Note that the mail::folder objects are not automatically destroyed; the application is still responsible for destroying any remaining mail::folders, after their a mail::account is destroyed.