Tips on setting up your own email server:
1. Don't.
2. Read first.
3. You still want to? OK.
4. Make sure certificates are OK
5. Only send over secure channels.
6. Don't test on remote servers.
7. Make sure DKIM and mail spoof records are setup properly
8. Have a static IP, that belongs to a business range
9. Spam filter
10. 99.9% of emails to hostmaster are spam. The 0.1% is important though

If you don't do 5 through 8 then you will get blocked or emails put into spam, forveer.