If so, that's not spamming, that's a sensible practice and most registrars do not charge for this service.
Or have you constructed one splash page and uploaded it to every keyword domain with all on site links pointing towards example.com?
That's not spamming however it's very unlikely these days. especially with Google, that they'll rank anywhere except towards the end of the SERPs.
This is an old trick that many of us have used in the past as soon as we bought domains to develop and avoid wasting time with launching a new site. It doesn't really work very well at all now even if you have tweaked the titlebar, tags and on-page content, the engines are mostly too sophisticated to be caught out.