| home page --- generated by a PL/SQL procedure which first stores the client's information of the current connection to a 'visitor' table and then generates links of query options. clients history can be easily pull over from the database. (fig. 1) |
| query the mailbox --- find out the summary information about the mailbox (fig. 2) |
| query the folder --- choose a folder from all folders currently available in the database (fig. 3), and find out summary information of the chosen folder (fig. 4) |
| All the above queries are summary information which are meta-data (accumulated or statistic data about basic tables) and produced at the time when clients requested (done by simple SQL calculation statements) |