Email is nonsensical for decades
I've thought email is a horrible system for a very long time.I'd like to point out some of the ways it is so and talk a little about why for some of them.
Predates widely available always online servers
Email was created before always online servers were widely and commonly available. Part of its very core is the ability to send an email to a relay server and have it forwarded on to its ultimate destination. That made sense when the ultimate destination at the time was in many cases a system that was inaccessible at the moment the email is sent.
That's no longer true with the modern internet. There is zero reason to do this in the modern age and it only causes problems now. You can and should talk "directly" ( routed through the internet ) with the destination from the very beginning.
Sure, even in the modern era it's possible for the destination to be offline, but very few people are relying on "mail servers" that aren't redundant and kept alive at all times. In the rare chance that the email server isn't available you can just wait and retry. Now... wait and retry is inefficient and if done badly can cause retry storms, hence the "store and forward" bits of email. But there are lighter ways to do this in the modern age.
Has no encryption
Okay okay so people have tacked encryption onto email. It works... badly. And is also inconsistent. Email was created a good 6 years before public/private key encryption was invented, so when it was designed the technology for encrypted messaging did not exist.
Today it does exist and is common and cheap to do. We should be using encrypted email always.
For that matter, all "email" should be end to end encrypted and the content not accessible by the "email provider." Even with current email systems today that are encrypted? That's not true. They can access your emails. This is ridiculous and unsafe in the modern era.
Having a way to layer encryption on top doesn't address that most emails remain unencrypted even if that is done.
Has no signing
Same ideas as with encryption, but messages aren't signed by anyone, so can be easily forged. For a very long time anyone could forge emails from anyone and you couldn't readily tell. At least today there are standards where the origin domain is checked, but that still doesn't prove that the person you think actually created the email, it only proves that someone with access to the domain sent it. So... because everyone these days uses bigco email providers, the bigcos can forge anyones email that they might want. Bigcos have to submit to the government, which means government can forge anyones email.
This is an issue when people consider emails proof of anything, and the government has incentive to deceive.
Formatting is horrible
Email supports a minimal form of html, and it is horrible. Layout is in desperate need of a revamp.
No "conversations"
Email itself does actually have tracking of what email an email is in response to, but it isn't handled by email UX consistently and as a result you still end up with Re: Re: subject text spam.
Additionally, because emails aren't signed, quoted sections could be changed by the quoter and no one would notice. This can be solved with quoting that actually is checked and verified.
Additionally, continuing to respond to an email does -not- mean that the subject has continued. Without a UX involving the user in a clear decision that it is a thread, it's still not an actual thread.
In the modern era we understand threading as we've had it in forums for a very long time and have it in modern incarnation in things such as Slack.
Timezones? What's that
If you've ever interacted with email with someone in a different timezone it is confusing, because emails themselves don't track the timezone of the sender or recipient. Without that information UI for email systems can't show it in a sane way.
The result? You end up having to set the timezone for your view of all of your email regardless of who each is from, which is just terrible.
Trust me bro. I'm tech support
Email has no inherent concept of roles within a company, so you end up with people just acting as a role with no real evidence to those they are communicating with that it is legit. Certificates issued by the company would solve that. Connected with signing, you could actually prove in court "this person acting in this role, said X".
No structured data
You may not be familiar with structured data and what that means, but the lack of it is a major downfall for email.
Imagine if all bills you ever got were not sent through physical mail, and all arrived cleanly in your email, and in a way you could see and know for sure exactly what company is billing you, for how much, and when it is due.
We could do this. Today. But we don't. Because reasons. One of them is because email has no concept of structured content.
Another similar thing is calendar invites. If you've ever tried to use Microsoft meeting invites with any software that isn't Microsoft, you are familar with the holy hell that is invites.
Structured data is also only the first step to a full business workflow system. Something we could do trivially today and would solve so many issues we all suffer from. I'm being vague here because this is a detailed conversation by itself.
wildnutmelon@aol.com
Email is not well suited to long term identity. The most direct example is because you can never change your email. You are stuck with whatever crap you chose for your email when you were... 12?
Sure you can make another email, but there is no built in way for people to know you moved to that new email address. That's good, in a way, I guess, if you want people to forget your email was wildnutmelon@aol.com.
Roles
Remember my brief mention of roles being important for business and helping prevent fishing. You should. That was only a few points ago.
There is more to it. An easier way to think about it even. When you go to work for a company they give you... another email. Wtf. This makes no damned sense.
Like ok, it makes sense you may only want to see work related emails, but it does not make sense if you want to see all stuff sent "to you". You're a human. Sure you act in different roles, but you want to have all your stuff together essentially.
Companies tend to like this because they don't want you to be able to have copies of your "work emails", but that is ridiculous because it conflates technological ability with policy for humans.
If you talk about personal shit with people through your work email, such as going out to lunch or when you'll hang out with them, you should be able to retain that content, not lose it to the void because "omg that's a work email and you just got laid off; kiss goodbye to all your work emails."
There is more to this besides just personal versus work as well. You should be able to have any number of "identities" by which you'd like to operate, and to easily be able to handle them all through one consistent system rather than have to have multiple emails.
Companies love this though. "You want another email! Excellent. Pay up."
Another example where the whole "this is your work email" bit disintegrates is when you work in open source that is "supported by your company." They want the credit, so they insist you use a work email. Only... you are effectively screwed when you leave the company because all the people in open source interacted with your work email address.
The corporate nanny
Ever had something you said in email privately used against you by HR? I have. In my optimal world messages should be private between yourself and the person you are messaging. Not spied on by HR nannies and used as a reason to screw you out of your job when you don't meet the 30 pages of acceptable behavior defined by the corporate cabal.
Note that I'm not arguing for protecting abusive behavior. The system I envision has all the messages I send signed by me and I become legally liable for every word of them if the recipient chooses to make that information public.
I'm not arguing against responsibility. I'm arguing against surveillance.
Update an email?
Have you ever wanted to correct an email you've sent?
It happens to the best of us. We say the wrong thing. We mispell something. Or we are just flat out wrong about something.
Email leaves you one option: send another email.
What if it supported simply showing people the updated email? It should still allow you to see the earlier revision of course, but that would be a massive improvement for many situations in my view.
I got married
You know what happens to many humans? They get married and change their name.
What happens with email when this occurs? Chaos. That's what.
The issue here is that the name associated with the email address is text that can change arbitrarily from one moment to the next. That's silly. That text should be associated with the identity, not with the email.
Anonymous emails
It should be trivial to create infinite 'anonymous emails', effectively just a gibberish identity you feed in when forced to for signing up for things to receive something from them.
This could be done very easily and feed into your own regular "email" and let you respond back to them without issue as well. Even provably as your real identity -without- letting them also spam you. Your identity does not need to be access to spam you.
Right now you are expected to keep your email private, because if you don't you get piles of junk email. That's ridiculous and runs contrary to what you want, which is having a public identity but still limiting who can send you what.
Permissioned contact
Above I mentioned structured content and alluded to workflow with email. There is a powerful thing you can do when you combine those concepts with "anonymous emails". You can make an address that is only able to receive a certain type of structured message.
For example, you could give a company -only- the ability to send you a bill and nothing else.
The possibilities here are somewhat endless. With a common set of types of common communication, you could effectively end spam permanently.
Subscriptions, RSS, and Notifications
A common use of email is mailing lists or subscriptions to some periodic content. That content is often sent to many people.
Email is a terrible technical solution for this. RSS was a loose attempt to do this more reasonably. RSS though additionally wasn't great.
There is, essentially, no common standard for subscribing to notifications that works in some way like an open protocol like email. We desperately need this, because it is silly to copy periodic content to everyone when essentially all that should occur is that they are notified that a new bit of info is available.
I do get that it can be nice to have the content be synchronized to your local computer or phone, but that doesn't mean that the content also ever needed to be copied to "your email server".
Two factor
Email is used to let people prove they are that person. This is horrible practice because it isn't done with a cryptographic identity and can be forged at many steps in the process.
This happened because email binds together identity with "way to receive messages". The two should not be bound together, and each person should own their cryptographic identity. That identity should never be forgable by a third party such as a company. You, the individual, should own and control your own keys.
Summary
There are yet more points that are problematic about email. The core issue is that email was meant for a very limited application and became the defacto default for internet non-chat messaging.
There are many ways to improve upon email. The extent of it is such that there is no point any more to try to improve email. It should be replaced outright. I am working on exactly that, and you can be sure I'm going to address as many of my complaint points about email as I can.
Because the most effective response to a crappy system such as email isn't whining about it. It is just creating a better replacement and then pointing at it.