You don't want to run your own email service ever
Email systems are hard. Like really really hard. What looks like a simple "Send" button to you, in reality is a sh** load of complex systems and services interacting to each other in complex ways to accept your email and push it all the way through to the recipient, where the same or similar sh** load of services do their magic to store that message and display it to you. Storage of ever growing data, spam scanners, rate limits, deliverability tracking, DNS problems, scaling problems, online reputation of outbound servers, all kinds of features and integrations to other systems. Add constant abuses, spammers, phishers and here you have it - a perfect hell.