That's why I become a software engineer. I would like to host the services and use cloud as backup.

Right now, the only thing bothers me is the email service. For a selfhosted email service, there might be some problems.

For example, I would like to sign up FB by my custom domain email address, but after roughly two days they treat me as bot and ask for cellphone which I don't want to give them. Because there is no way to delete the cellphone later. The function on their setting is not working. Even if you deleted the cellphone on setting page, you could still get targeted AD by hashed cellphone information. It seems like they use hashed information as the way to against user deleting.