[Dovecot] Ignore purge and delete command

[vikrant at linmark.com]

Hi,

Does anyone know how to ignore the purge or delete command 
from the imap clients.

Actually I created a mail archive and using dovecot and so far I am 
happy with the performance. But the problem I am facing right now 
is I do not want the users to delete the mail by themselves and want 
to disable the purge or delete command.

Thanks
Vikrant