But I found Linux, the free / open source software community, and the pirate community in the 90’s. Since then it’s been pretty obvious to me that every computer has an administrator and that I’d prefer if the administrator is me. Stuff like “the cloud” and “apps” isn’t going to distract me from that point.

No.

Having a couple emails end up in spam boxes isn’t that big a deal for many self-hosted app scenarios.

For example, if you have a limited set of users, the setup process can involve getting an email and marking it not spam.

Delegating mail to an external service means you’re not self hosting it.

Sending email is something you can just do. There’s no need for an external service unless:

• You’re trying to deliver email to external users.
• You really need your email to get through without ending up in people’s spam folder.