When files are uploaded via Cryptshare, they are
uploaded through a secure channel, but are not encrypted
themselves yet.
Once they have reached the Cryptshare server, you can
pre-process these files before they will be stored
encrypted. This means that you can run external programs
against these files e.g. to check them for viruses.
Depending on the return code of the external program, the
file will be processed further (i.e. stored encrypted and
notifications sent out) or rejected. In case of rejection,
the user will see an informational message on the screen
that his files could not be sent.