[kube-system]

> Comparing PSTN to instant messaging walled gardens is interesting, but I’d argue the real parallel is email: a federated, open standard that also suffers from spam and abuse, yet still manages to limp along thanks to heavy filtering and layered trust systems.

I think you're absolutely right to draw that parallel. But, today's email landscape isn't much of a federated open standard. It's a web of trust and distrust, filters, and deliverability issues. It's real work to maintain an email server and attain high deliverability with other email services. So much so that most don't even do it anymore. Most email is just delivered by a few large providers.

Really, email is suffering from a lot of the same issues that PSTN also suffers from. But email providers just decided to "solve" the problem themselves, mostly by taking a heavy hand at blocking things and deciding they don't really care if you're not a big provider.

[unsignedint]

Yes, absolutely — I’m not suggesting email is anywhere near perfect or free of abuse. But at least collectively, the layers of filtering, reputation systems, and standards make it usable for most people most of the time.

The key difference for me is that the PSTN moves at a snail’s pace, maybe because of regulatory entanglements, maybe because of interoperability constraints. The result is that problems which have been rampant for decades — spoofing, spam, robocalls — remain trivial to exploit. Email has plenty of its own problems here, but at least you get more signals to work with (headers, DKIM/SPF/DMARC, filtering, etc.) than just a string of 10–12 digits with no real context.

That’s why I’m less inclined to “cherish” a system whose shortcomings shift so much burden onto the end user’s well-being, all in the name of interoperability. If interoperability means putting up with abuse at this scale, then that interoperability isn’t worth much — and that’s where my frustration comes from.

[kube-system]

> at least you get more signals to work with (headers, DKIM/SPF/DMARC, filtering, etc.) than just a string of 10–12 digits with no real context.

For most people it is a distinction without a difference because they know about as much what to do with a DMARC policy as they do an SS7 frame.

DKIM/SPF/DMARC as bandaids just as much as STIR/SHAKEN are, they just need to get a kick in the ass to implement them -- on both fronts. I get tons of official and sensitive email still from domains that fail DMARC.

[unsignedint]

Sure, but my point still stands — you have more tools to work with in email. For what it’s worth, I can usually contextualize a message from the subject line and the sender’s address without needing to dive deep into headers. (Phishing is definitely a real problem, but it’s not unique to email in this discussion.)

Now compare that to the PSTN: what does 555-123-4567 really tell you? Not much. It’s just a string of digits with no inherent context. And unlike email, I can’t even choose to outright refuse delivery of a call at the network level.

[kube-system]

> Now compare that to the PSTN: what does 555-123-4567 really tell you?

It tells you exactly as much as the "from" field does in your email.

> you have more tools to work with in email.

Only if you're an engineer implementing a mail server configuration. But if you're implementing a telco you also have more tools to work with than a caller ID.

End users use DMARC/SPF the same way end users use STIR/SHAKEN... they don't. None of them are user-servicable values. And service providers use DMARC/SPF the same way end users use STIR/SHAKEN... they implement those controls for their users in the form of a managed service.

[unsignedint]

Even if I don't run my own mail server, I can still open an email header and see context. Last time I checked, I can't walk into a telco and ask for the telephone equivalent of that. On PSTN, there's nothing beyond a bare caller ID string, and that lack of context is exactly why I see it as a problem.

Email gives end users multiple signals and filters to work with. PSTN doesn't, and that's why I disagree with your equivalence.

[kube-system]

DMARC/SPF/DKIM are not something that users can take advantage of by reading their email headers, because it is nonsensical to end users.

You can take advantage of it because you're an expert. Just because email vomits out more information that are useful for experts doesn't mean it is better as a real world system for normal people who use it.

[mulmen]

You have more tools because the market created them because it’s a federated protocol. The PSTN is a different case where market forces don’t align incentives with spam reduction. This is why regulators like the FCC exist.

[unsignedint]

I get the distinction you’re drawing, but that just brings us back to the same fork: if decades of FCC involvement haven’t produced a trustworthy caller identity system, then the reliance on regulation isn’t solving the structural weakness, it’s just propping it up.

At that point, we’re repeating the same values clash — you see regulation as a workable fix, I see it as evidence of fragility. I don’t think continuing this line is going to get us any further.

[mulmen]

Why are you so eager to give up interoperability when it’s not the problem? Spam exists within walled gardens too. Interoperability and spam are orthogonal.

[unsignedint]

I’m not “eager to give up” interoperability — I’m saying interoperability without trust isn’t worth much. Calling it orthogonal doesn’t change the lived reality that the abuse rides on that interoperability at scale.

If the only way to preserve interoperability is to accept decades of unresolved abuse and perpetual patchwork fixes, then that’s not a trade-off I find compelling. At that point we’re not debating facts, we’re debating tolerance levels — and mine is lower. I think that’s a good place to leave it.