[CentOS] email Server for CentOS 7

Mon Oct 1 15:37:46 UTC 2018
Peter Eckel <lists at eckel-edv.de>

> On 29. Sep 2018, at 23:58, John R. Dennison <jrd at gerdesas.com> wrote:
> Save yourself the effort, time, headaches and eventual bloody tears of impotent
> rage and just go with Google or some other provider. Running a mail
> server properly is one of the more difficult tasks and quite often not
> worth the time and trouble, especially if one is asking about it on a
> list such as this.

I fully agree with most of the former, except for the Google part. Google is to privacy what a shark pool is to a carp. If possible, avoid Google at all cost, and particularly for E-Mail. There are services around that cost a very small amount of money (e.g. mailbox.org or posteo.de), provide a very reasonable service and do *not* peek into your mail for advertisement targets and sell your data to their customers.

If you want to run your own mail server (there are good reasons to do so, I've been running my own services for many years now) be prepared for a learning curve, as mail is not as simple and straightforward as it looks. You should also run your own DNS in that case, as many modern features of secure mail services are tightly linked to DNS (e.g. SPF, DKIM, DMARC etc.). DNSsec is preferred. 

There are some good books around (e.g. the Postfix/Dovecot books by Peer Heinlein, who incidentally is the owner of the mailbox.org service, but the Postfix book only seems to be available in German). Without a good foundation on running mail servers and/or some help from experienced mail server operators you're almost certain to screw up big time, which in most cases means ending up on some blacklists or having mail delivered very unreliably. 

As for the software question, I recommend the Postfix/Dovecot setup, enriched with some additional components to support graylisting, virus checking, spam filtering, DKIM, DMARC and SPF.