For a while, my home mail server has been broken; that is, ever since I decided to install ESXI and virtualize everything, I never bothered to fix the mail server. Moreover, I also migrated away from Cent OS 7 to either Ubuntu 20.04 LTS or Rocky Linux 8. Ubuntu came first before Rocky Linux 8 was available. I didn’t count Cent OS 8. The result was a collection of broken config files that I had to migrate over and inspect to make sure the config wasn’t broken, or worse, permissive to the point of allowing hackers to use my lab for cyber attacks. Thankfully, some things were easier to migrate than others; the BIND config was just a copy and paste operation mostly, but other things, like the Strongswan IPSec configuration required complete restructuring.
This resulted in several services that are not critical to nominal internet access at the house being shelved indefinitely because of a combination of school and other things that would keep me from migrating everything to the new configuration. Another important point that is relevant to mail servers is that I used to route my smtp traffic through an smtp relay because my old ISP would block port 25, and I had a dynamic IP assignment. To clarify port 25 is still used to communicate between smtp servers; this is not referring to e-mail clients like Thunderbird or Outlook that can talk SMTP over port 465 or 587.
However, my old ISP is history now. I migrated to a gigabit shared fiber link, and also got my hands on a /29 address block. In other terms, I have 5 static host addresses to play with in my lab environment. So far, I am using 4 addresses for things like a TOR relay and the like, which means that I have one more address available for configurating the mail server. Port 25 is blocked, but it can thankfully be unblocked if I say the right things to customer service; I’m not entirely sure on that statement until I actually try it, however.
Next up in part 2, I will explain my experience resurrecting the mail server without using any SMTP relays as I find more time to piece together the old postfix and dovecot config files.