The hardest thing in setting up your emails server is to keep your messages out of spam folders. Even if you are completely legit company that sends out ONLY human-written personal emails, you will get tagged as spam first.

I've self-hosted for about 2 months, and promptly switched to iCloud. Just because I've been spending too much time calling people and telling them to check their spam folders.

Recently our business moved to another domain. We had a guy who has spent over a month "warming up" traffic, so our new domain won't be tagged as spam by default.