with V8.12 sendmail,
vacation logs all its error and warning messages
via the syslog(3) facility (Section 14.3). Warnings are logged at LOG_NOTICE, and
errors are logged at LOG_ERR.
The syslog facility reports them like this:
Mar 1 13:30:05 lady vacation: vacation: can't open mailbox database: Service
If you prefer to have these errors and warnings printed to your
screen, you can use this -d command-line switch.
It is better used outside your ~/.forward file
because otherwise, printed errors will be sent to
sendmail where they might be lost. You use the
-d command-line switch like this:
% vacation -d bob < /dev/null
vacation: no such user bob.
Here, the administrator is about to set up a
~/.forward file for a user, and tests the
vacation command with this -d
switch. Because the user is bbob, and not
bob, the error is immediately evident. Without
the -d, the error would have been logged, and that
log message might have been sent to another dedicated logging host.