Cold emails are spam, unless those people specifically opted in. And it'll harm your product, probably... Blasting 50k scraped or purchased email addresses from a primary startup domain is one of the fastest ways to permanently brick any company's communications infrastructure.

Modern email providers track sender reputation primarily at the root domain level (your .com). Doesn't matter if you send via a service with a different IP than yours.

And the spam threshold today is 0.3% (that is just 3 people out of every 1,000 clicking "Report Spam"). If you're over the threshold, you're auto-flagged.

In short, you'd surely get severely penalized, and your host/registrar are also gonna get mad. Don't do it.