Opensource.com - https://opensource.com/article/18/3/host-your-own-email
There are plenty of reasons not to want to hand off the tasks of storing your data and running your services to third-party companies; privacy, ownership, and avoiding abusive “monetization” are some of the top ones. But for most people, the task of running a server is just too time-consuming and requires too much-specialized knowledge. Instead, we compromise. We put aside our worries and just use cloud-hosted corporate services, with all the advertising, data mining and selling, and everything else that comes with them.