I cannot speak for other software available in the marketplace, but
Paigham Bot allows you to include keywords, shortcodes and filters for niche-specific campaigns. Once your campaign settings are to your liking, it will automatically send out your message to hundreds (or thousands) of websites using contact forms.
It's been a while since I've used it to be fair so I'm assuming theres now more features available. The devs seem to update it regularly, there's a ton of tutorials and it's still going strong.
@Cratos should be able to assist you further with any questions in the
official sales thread.
Note: I'm not affiliated with Paigham Bot in any form, just a previous customer.