Let's say I want to receive emails from my website gnarlodious.com, which runs on Server 10.6. How do I set that up? All I want is simple POP and SMTP service for one domain. Seems like it should be easy to get going.
Sorry I searched Google for hours but found no clear instructions. I think I figured out that Postman is for mailing lists only, not email accounts. There is also a squirrelmail, but it looks like it is only for viewing webmail. Also found Postfix, which might be what I am looking for. Please explain this abundance of mail software.
Screen shots are not necessary. Your reverse DNS is wrong, or (if it's been changed) the changes haven't propagaged through (yet). You need to fix that setting with your ISP; with whomever is providing your IP address.
In simplest terms, here are the Terminal.app commands:
dig +short gnarlodious.com
dig +short -x your.server.ip.address.here
dig +short MX gnarlodious.com
do not match.
Here is what I see from here:
$ dig +short gnarlodious.com
$ dig +short 126.96.36.199
$ dig +short -x 188.8.131.52
$ dig +short MX gnarlodious.com
Your forward DNS is 184.108.40.206. Your reverse DNS is 82.nedernet.81.183.65.in-addr.arpa (a PTR or pointer record; that's the reverse DNS) and spurious alias (CNAME) gnarlodious.nedernet.net. This does not match. This misconfiguration means that many other SMTP mail servers will interpret this as a spam engine, and won't play.
You have no control over "ignoring this" as this is derived from your external DNS by other servers; any attempts to set this to be ignored won't have any effects on the other mail servers that might interact with your mail server. (Yes, you can get a few messages through, though inbound and outbound messages can and variously will be dropped due to the DNS errors here.)
(I also haven't checked to see if the ISP has erected any blocks against mail servers. If you're on a static IP, that usually should not be the case. But it's worth confirming the address regardless, as mistakes can happen, and rogue malware that breaches your server can get your server listed.)
As for ignoring security, a successful breach can get your server listed in the spam engine listings, and that takes more time and effort to clean up, on top of cleaning up the breach. And it's not like the folks won't attack the servers; my most recent batch of servers connected to the net were attacked within minutes of the initial connections, and that was before any notice or any external DNS had been set up.
Running a server operating system means knowing a little bit about IP networking, about DNS services, server and network security, and some other low-level pieces, or to have access to a support organization that can assist you with these tasks. Server configurations - even as simple as OS X Server is - still require an investment in acquiring some related knowledge; more than does running a client system.
I am a customer of one of the various hosting services that's available around the Internet, and I spend about US$50 for the hosting per year, plus some for various DNS registrations. Which means I can re-allocate the time and effort I would have spent on that task, on other tasks. Put another way, how do you want to spend your time? Learning about and running a server? Or getting (other) work done?