> Almost none of the things linked there are run by serious isps that are responsible for other peoples' mail in quantities of tens of thousands of inboxes or m

> Almost none of the things linked there are run by serious isps that are responsible for other peoples' mail in quantities of tens of thousands of inboxes or more. The whole point of self-hosting is precisely so that no entity runs tens of thousands of inboxes. If it's good enough for your personal use and the few people you're willing to help, then it's perfect.