Plunk: The open source email platform

> If the bombs drop and civilization is over and me, and my home lab are the only survivors, can I still use that software?

which rules out any software used to connect to non existant other servers or people.

Sure, the software "works" .. it just doesn't do anything .. ie. it can't be "used".

In the before times, I helped build and was a lead engineer on a team building a delivery platform from scratch, with very minor composition bolted on. (For a time reference, this was before HTML email was even common.)

Some of the lessons from then are very relevant still today. A big one that comes to my mind is 'idempotent' email isn't really possible, because SMTP has no 'send iff message-id has not been received' primitive. You can get to try-send-only-until-2.5.0-code, but even that can be non-trivial engineering. We went to a rather large degree of effort to do that ourselves, since repeat emails are a terrible signal, but I think thats only a marginal benefit to the larger operators.

Idempotent delivery even isn't a direct benefit to advertisers or most sending actors: Primarily, for the majority of the market, they don't really care about duplicated deliveries below some statistical model, since the costs are heavily externalized. Secondarily, since those parts of the industry depend on out-of-band read-indicators, engineering to improve delivery idempotentcy doesn't reflect into a market advantage.

Email's gotten prettier in the two decades since then, but its quality at every point in the stack I think has gotten worse. I routinely have to firewall whole ASNs because the bigger bulk operators (salesforce marketing cloud im looking at you) have no functional mechanism to call out particularly spammy customers, and thats after aggressive greylisting. Sure, the greylisting cuts out >95% of my spam, but the noise level on that last 5% is still horrendous. Forwarding with headers to abuse@ should be a universal paradigm but thats 99% a noop these days.

Given the lesser upside and relative difficulty of the delivery problem, it seems only natural that most of the effort in email platforms these days is in composition. Even if you want to work on the delivery half, with IP reputation, aggressive antispam, and the general enshittification of all things email, the barrier to entry is orders of magnitude higher than it was in 2000. I don't want to say its impossible, but I think you'll have a bad time if you're trying to do it anywhere that doesnt have enough size/inertia or money that email receiving operators choose to negotiate with you rather than preemptively block you.

That ircd servers in the example above can still be used with a bot as an automation tool (at that point as the only survivor the security would be the least of your concerns), as a way to invent imaginary friends to pretend your life is less miserable, whatever.

Or say you have a mastodon or pixelfed instance. Sure no other instance will ever connect and no other user will ever be able to see your posts...but you. Which could include some fond memories you want to keep.