When I last looked into setting up my own email server, I read that your messages ending up in the spam folder was almost inevitable if the receiver is using a major host (Gmail, iCloud etc.) Is that still an issue?
However, when I set up my first email server most emails were delivered just fine, however emails to a Microsoft domain (hotmail, outlook, etc) all were marked as Spam.
Then I switched to a new IP and since then everything has been great.