in reply to Limit submissions over time?
You might find the scripts here to be of interest, since you are a relative newbie doing web programming. The NMS Project was organized and is supported by several contributors to this site who have quite a lot of practical acquaintance with CGI programming with Perl. The form-to-email task in particular is one that has been performed many many times, so you might want to see how somebody with experience has done it.
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Seekers of Perl Wisdom