Can I send back an unsolicited email to a recruiter about my HR product?

Hey all,

Quite regularly, I receive unsolicited emails from recruiters using some third parties which is basically scraping my data or via the Linkedin API.

Since they are giving me their email, I was wondering the following questions:

• Is it legal to sell/give a list of recruiter emails to a HR software company?
• Can I send emails about my HR product directly to them?

Thanks