Email business

I was born day before and yesterday, became aware of a niche called "email marketing" business. Popular ones are AWS SES, Azure communication services, sendgrid etc.

I want to start my own "emails emails emails" business. I read some posts that warn against it. Some strong points against the idea are: oligopoly blackholing almost all IPs unless those IPs belong to the big tech companies & hard time finding IPs with clean history.

But the point that sticks with me the most is that any company that uses a large cloud provider would choose to use their "emails emails emails" service for purposes such as easier integration. This reason is a big enough reason that would deter me from going out of the cloud provider's services fence.

Please teach me more.