Call to undefined function t()

Yes, there it is again. This time for D6, in the case where form submissions are dropped and the user is notified.

includes/common.inc should be sourced before calling t(), as you know.

I also modified something else; changed the severity of the drupal_set_message() call to 'warning'. IMO the "we dropped your form submission" deserves a higner attention-grabbing level from the user.