I'm not an expert on laws, GDPR, when consent is needed, by whom, etc.
This is a side project that just started gaining a little bit of traction, and I'll certainly look into all the above.
However, the emails I add are publicly available, found on the internet. Not from some leaked database.
I also have prices high in order to keep spammers away and have a small handful of customers. I only have about twenty, and they are targeting different kind of startups.