If it helps, I recently rebuilt my mail server and changed from FreeBSD+qmail+Courier to Ubuntu+Postfix+Dovecot.  In doing so, I used this series from Ars Technica:<p><a href="http:&#x2F;&#x2F;arstechnica.com&#x2F;information-technology&#x2F;2014&#x2F;02&#x2F;how-to-run-your-own-e-mail-server-with-your-own-domain-part-1&#x2F;" rel="nofollow">http:&#x2F;&#x2F;arstechnica.com&#x2F;information-technology&#x2F;2014&#x2F;02&#x2F;how-to...</a><p>It shows how to set up SPF, DKIM, TLS, anti-spam filtering, Sieve, certificate-based authentication (I still haven&#x27;t figured out how to do this with an iPhone), and so on.  The only bolt-on it references but doesn&#x27;t explore and I actually used is the Z-Push package to implement ActiveSync.