> Email aside we can learn a lot from this kind of distributed, decentralised system design in the future.

Nit for other people curious about email: email isn’t decentralized by the popularized use of the term, both in theory and more so in practice.

Email relies on DNS which is federated. That doesn’t mean that it’s worse, federation is a proven-to-work trade off which provides many of the benefits of decentralization, (arguably the most important parts).

As for practice, email relies on opaque reputation systems to prevent abuse, which acts as a centralizing force. I’m sure you know (better than me) that the barrier of entry to sending email on your own is quite a bit above zero.

> Email relies on DNS which is federated

To a great extent, yes.

If I give my public email address to someone and expect them to be able to send me email from anywhere at anytime, they will almost certainly have to rely on the DNS that exists like we know it.

But the situation can be slightly different in various ways:

- If we our mail servers have globally routable IP-addresses permanently assigned to them, and are set up to accept mails where the IP address is used directly, we could use the IP addresses instead of domain names. But that's still similar to the situation with domain names, since it's still ICANN at the top for that too.

- In a LAN or a VPN we could exchange email between hosts using either DNS that is completely under our control, or we could use mDNS on it which is also under our control, or in the case of either really small networks or a short time span we could even rely on the IP addresses our mail servers have on said LAN or VPN and send mail and again that would be completely under our own control as well.

- Since Tor offers a base for TCP connections, every TCP based protocol can operate on top of it. So if we both use Tor connected email servers then we could exchange emails that way. Our email clients could connect to our email servers over clearnet without having to be aware of Tor, and we could use email addresses like bob@fastrcl5totos3vekjbqcmgpnias5qytxnaj7gpxtxhubdcnfrkapqad.onion and [email protected]

In these ways, e-mail could still be regarded as decentralized. As well as in a simpler way that as opposed to for example Facebook where there is one company that owns the whole system and oversees and decides who gets to have an account on the system or not, you and I can always find another e-mail provider to give us a new account and we can communicate with others from that new account.

And in fact, if we were willing to do it, we could change how we set up our e-mail servers so that we have the server accept mail from any other e-mail server but with the condition that the mail was encrypted with a known PGP key. Now imagine that you and I set up our mail servers like this and we exchange PGP keys. Then even if I lose access to my original email account that I had told you about, I could mail you from a different account with another provider using the same PGP key, and your server would recognise that the mail was from me and accept it and then you could respond back. But what if we both lose access to our accounts at the same time? If we plan ahead we could make not just one account each but a number of accounts on a number of different mail servers that we both tell each other about. That would give us quite a lot of wiggle room.

Few things are perfectly anything, and email is way more distributed than (say) Twitter messages.

In particular, I own my own domain (which costs little), and then set up where my email goes. If I want to change email providers, I can do it without having to track down everyone who knew my old email address. Similarly, if I don't like my domain registrar, I can change that too.

Being able to control my own destiny, and not being completely under the control of someone else, is in my opinion the real goal. Distributed & decentralized systems at least hold out the promise of meeting that goal, and where they do, I'm delighted. It's not perfect, but it beats many other systems.

To add to that, while DNS is centralized at the root, that centralization is unavoidable if you want to have human-readable addresses that consistently resolve to the correct recipient. And each TLD is (at least the ccTLDs and the old gTLDs) managed by a government or international organization acting on behalf of governments, which in turn (at least in theory) act on your behalf. While this system is not perfect (see e.g. the US governments history of seizing domains) it is almost infinitely better than most other communication mediums on the internet where the single company operating it can kick you out more or less for arbitrary reasons and without recourse.

That alone makes this system precious enough that any pains from running your own mail server are IMHO worth it if it means that we can preserve Email as we know it - as a federated system not under the control of a single or a small number of corporations. Unfortunately, Email is at risk. For a lot of people it is already synonymous with Gmail and while Gmail is hardly the worst when it comes to deliverability (IME that crown goes to Microsoft) they do control enough accounts that they can pretty much nuke your little server if they want to.

> the barrier of entry to sending email on your own is quite a bit above zero

I can attest to this. I ran my own email server with no problem for fifteen years. Then my provider was acquired, and I decided to switch to a different provider, and so the IP address of my server changed for the first time in 15 years. I have not been able to reliably send email since, and I finally threw in the towel and signed up with Fastmail to handle my outgoing email.

The biggest problem is people banning entire blocks of IP addresses. This can give you a bad reputation even if your behavior is stellar. All it takes is for someone using the same hosting provider to be a spammer to get yourself blacklisted.

The whole situation sucks big fat honking weenies.

Thanks for the data point. That sucks.

I guess generally speaking, federation works well for DNS itself but not so well for email, since the malicious stuff you can do with DNS is greatly limited. Abuse/spam is everywhere, not just email, and the sad part is that providers not only went and rolled their own anti abuse systems, but they also went to great lengths to keep them secret.

Without solving the spam problem, we won’t see decentralized or even federated systems widely popularized for any products which has these incentives. This includes mastodon, Nostr etc. The worst part is that projects can become pretty big before the spam starts, so it kills projects at the worst possible time. I wish the FOSS community came together and focused on finding solutions that work, because decent abuse prevention today is neither easy nor cheap to get right. And going without one is a ticking time bomb.

No, it's not a fundamental problem. It's just laziness on the part of many email providers. My email server has proper SPF records, and so anyone whose email server is configured properly can easily verify that my server is authorized to send email on behalf of my domain(s). But email admins just subscribe to blacklists and follow them blindly. There are a few big players, including Microsoft and AT&T, who just don't care if a few small players get blocked by false positives. (Ironically, despite their tolerance for false positives, they still let through an enormous amount of spam. I know this because my parents have their email on AT&T.)

Spam and forgery aren't the same. I can be 1000% sure that you own the sending domain, that the mail came from an authorized server, etc., but that tells me absolutely nothing about whether I want to read what you're sending. Spammers used to be lazy and not configure the whole stack, so that became a simple heuristic, but these days it's nearly trivial to set up automatic provisioning of new domains and IPs with full SPF+DKIM+DMARC setups, so the big players went back to blacklists and IP reputation.

Spam definitely is a fundamental problem of all open-inbox systems like email.

Yes, that is certainly true, but in this case it is irrelevant because it is my server's IP address that is being banned. I am sending email to people with whom I have been corresponding for years (like my parents) and it is being blocked simply because the IP address of my server changed.

Parent poster here. Assuming malicious actors can easily set up all the fancy acronyms to verify the sender’s identity, how should spam be prevented if not through IP reputation (and whatever else they have today)? Should the reputation apply to the domain name instead? Would that protect against Sybil attacks?

To my knowledge, these systems are proprietary, obscure secret sauce heuristics. My point is that we should find a way to do spam prevention in an open and easy to implement way. Such an algorithm could then be applied to any open-inbox system, not just email.

> Assuming malicious actors can easily set up all the fancy acronyms to verify the sender’s identity

How is a malicious actor going to set up a fake SPF record for my domain without compromising my DNS account?

It makes sense to block a domain even with a correct SPF record. It makes no sense to block an IP with a correct SPF record for a domain that you already trust. And, like I said, I'm getting bounced mail from people I've been corresponding with for years, so I know the recipient email providers do trust the domain. They're just being stupid with IP black listing.

Just to be clear: Due to email forwarding, having an SPF record isn't enough for domain authentication; you also need DKIM and DMARC. Mailbox providers want to deliver emails that people actually want to get, so not relying only on SPF records is a reasonable policy. But yes, thanks to domain authentication, we should be able to move away from IP reputation to domain reputation – at least in theory.

See my response here: https://news.ycombinator.com/item?id=34869796

And setting up DMARC opens you up to an entirely new type of spam: corporate networks emailing you every time someone spoofs you. I had it set up for a short time before I quickly turned it back off.

For one thing, you can configure a DMARC policy without a reporting address. For another thing, you can use third-party services, such as https://dmarc.postmarkapp.com/, to aggregate DMARC reports for you (if you're fine with the privacy implications of that).

You can also just set up DMARC without a reporting endpoint. But DMARC aggregate reports are very useful, so I wouldn't recommend using DMARC without reporting. Also, you do not receive a report 'every time someone spoofs you', but rather periodically, at an interval which you can even configure.

That said, DMARC aggregate reports are not supposed to be human readable. You don't want to set the reporting endpoint to your personal inbox. You need a DMARC aggregation tool, such as included in https://www.mailhardener.com to process them. (full disclosure: I work there)

I have some procmail rules set up that sends most of that stuff to a different mailbox that I never look at.

IMO the mail spam problem is overstated. For technically inclinded people, sorting through the trash does not take a significant amount of time (at least it doesn't for me) and people don't complain as much about physical mail spam or ad spam being everywhere - or at least demand laws going after the spammers instead of dropping mail based on heuristics.

As someone who also tries to run his own mail server, this makes me laugh ;)

For those who did not immediately grasp the parents claim that DNS is federated and not decentralized; here [0] is a nice article I found that talks about network architecture terminology definitions used in various famous research papers. It is a very nice, terse, compare and contrast.

[0] https://networkcultures.org/unlikeus/resources/articles/what...

Thank you for sending me down the rabbit hole klabb3! :)

Thanks for sharing, I think I'll use this over Postmark. Just spent ~10 minutes looking over the site and the blog. Seems super solid.

Seconded, especially re RFCs. I built/am building on the client/personal user side, and agree they're really accessible. Of course what I've done is still riddled with bugs, and my hours spent on it are few and far between, but it's fun to build something to such a common protocol; have it work and interact with others.

I was finally pushed into getting it off the ground when Fastmail stopped working the way I relied on it (niche/awkward/not documented as explicitly working) a week before my renewal - so I spent long nights getting something usable off the ground with that as a deadline. Extremely satisfying. (Then Fastmail started working as it had again, a day or so before my time was up! >_<)

Out of curiosity: What's the "feature" you needed; and what for?

I can't remember exactly what aspect broke - though I think I have notes on it somewhere because I intended to blog a bit about it (not to hate on Fastmail, just to explain what I was doing and how I fixed it) - but it was something to do with relaying email, i.e. delivering it 'envelope to' my Fastmail address, but addressed to another.