The vdeliver utility performs the vacation tasks. It performs this tasks
for a given user if the DB file exist and there is a vacation message
(The DB file collects the address who have received the vacation message
so far). Now the DB file may also contains a start and stop date for the
vacation service. One may setup a vacation message in advance.
Currently there is no user interface to handle this. The format in the
file is simply a line
#date: start_date end_date
The dates are encoded using international convention yyyy/mm/dd.
The old behavior is preserved (A db file without #date: means the vacation
processing must be done).