This post [1,2] from last October discusses a major problem with hosting your own email, which is that the big email providers pretty much reject your messages until your "reputation" is good. The reputation concept is purportedly a spam fighting effort, but a more cynical view is to see it as an effort by the big providers to sabotage self-hosted email. More discussion here [3] and here [4].
[1] Original post, now defunct: http://liminality.xyz/the-hostile-email-landscape/
[2] Thank you archive.org: https://web.archive.org/web/20151121132739/http://liminality...?
[3] https://news.ycombinator.com/item?id=10405681
[4] https://lobste.rs/s/ckfyqd/the_hostile_email_landscape