Very. It's content delivery in real time, latency optimized, what this is about. P2P, using residential low-speed links and desktop computers, is simply not suited for the task.
What is not is new. Distributed content caches were all the rage at the end of last millennia - everybody remembers about Squid, I guess? - and DNS geo load balancing (including fancy boxes with large price tags), and all that stuff. Ever fatter pipes have always reduced the need for this sort of solutions and my guess is that it will continue to be the case.
Multicast is another example of a technology that was created to improve content delivery, basically for audio and video. Almost nobody uses it. Instead, CDNs distribute unicast feeds globally. It was also a good idea, but it required a ton of resources and a different thinking than traditional routing.
A long time ago, I purchased a surge protector for a customer that was losing modems like flies on a remote site. "Just plug it this way and put this green and yellow cable to earth", were my instructions. Further modem losses made unavoidable to pay a visit to the remote site. He did put the green and yellow cable to earth... between the table and the floor.
Well, considering that the guy was a biologist, I called it a honest mistake, gave some further explanations, and never heard back about fried modems on that site.
On a slightly more on-topic note, I lost most computers to upgrades. I know I'm not supposed to complain about lack of options, but...
civil war is certainly still a possibility.
So, what do you call the current situation?
2. A block of 24-32 ip numbers. (49 ip numbers would be ideal, but it's harder to buy odd blocks like that.) Put your mail server as close to the middle of that range as possible. It sounds like a lot, but most collocation facilities can hook you up with this for 300-500 usd a month.
While most of your advice is sound and I can understand your frustration with running e-mail servers, I think that the quoted part is ill advice.
You are going to make a hoster rich for no good reason at all.
I manage some IP space (by that I mean something bigger than a couple servers here and there). Parts of "my" space, predictably, have significant e-mail traffic. This introduction is just for you to give me the benefit of probably knowing what I'm talking about
Yes, there are a few blacklists so stupidly managed that they will blacklist a whole block if they get hit by a single IP on that block - and by the way, the block size that those morons usually choose is not 50 IPs, but more often 256 - yet another remainder of the classful days that resists to die. And this is the reason why few people use those lists, and are therefore not a usual problem. In the rare occasion where one of my mail servers, or other people's mail servers in "my" IP space, hit something like that and I need to be involved, I inform our user(s) and the other party of the situation and make it very clear both to our user(s) and to the other party whose problem is it to solve (with rogue black lists, definately not ours), and that if they stop using blacklists managed by former members of the nazi party, they will be much better off with not measurably more spam, provided that the rest of their side more or less well implemented.
Aside from the network, I manage directly a few mail servers. While it's a never-ending work to keep them tidy (with most of the work being indeed made one time at the beginning), it's not horrible. I know because managing mail servers is not near the top of the list on things in which I spend my time, by far. Which is why I keep doing it, despite the valid reasons many posters have explained in favor of Google Mail or some other big provider, and despite not being the focus of my job.
Currently, my recipe is graylisting+SPF+reverse deliverability tests+a few obvious compliance tests+a couple sane black lists+two white lists (one in-house, one community)+fail2ban, running on Postfix and Dovecot, and Roundcube for webmail users. The only thing that from time to time causes me to look at logs is the reverse deliverability tests, and I could do without them, but I choose to be a little bit less flexible there. My implementation is based on the excellent workaround.org tutorials by Christoph Haas which I already recommended, I think, on this same discussion.
"I think trash is the most important manifestation of culture we have in my lifetime." - Johnny Legend