[kilburn]

Also, they would school them on actual-world problems in the process:

- You can't wait until you receive the entire body to be able to compute a signature to then validate the sender as your first line of defense. It is just too expensive and opens you to DDOS attacks. People use IP reputation as a first line of defense because it is cheap, not because it is good.

- You cannot enforce people's behavior through RFCs. I can assure you that random guy next desk will not care about your "this is a top-posting-thread" header and bottom post there. Even if she has to manually copy/paste things around.

- Likewise, auto-generated plain-text versions of HTML (or other rich-text formats) are no better than what screen readers can achieve. Most poeple won't bother writing that alternate version, meaning the obligatory alt text is now less useful than when it was optional and only people who cared inculded it.

- Your largest client may not update their e-mail infrastructure to comply with the latest standards. If that happens, you don't tell them to update or otherwise you won't be answering them because their e-mails go to spam. You do whatever is necessary to ensure that their e-mails don't go to spam. Business always comes first.

[gjsman-1000]

Hypothetically, while I’m no expert:

1. Could a future protocol require an immediate initial message (a “hello”) stating exactly how much content will be sent, and until the “hello” is sent, it’s limited to, say, 128KB before the connection is immediately terminated? (And of course, if the content exceeds the declaration, termination and immediate IP temporary ban, safe to do as this is an obvious violation of a new spec?)

2. The goal is to make it easier for the email client which by itself will encourage good behavior. There’s also no requirement for the messages to all be in one massive blob.

3. The goal is that it would be automatically created by the client. For personal emails, this is easy. For enhanced HTML emails, that is where the requirement comes in. Email providers can come up with their own ways of enforcement from there (I.e. “if it’s only one sentence, you obviously didn’t do it”), though I get your point and that would become messy unofficial spec again.

4. Could a future emails system have versioning, allowing the server to clearly communicate (“Hello, I implement MX2 v3.1.”)? In addition, a business can obviously make their own settings that original email alerts do not go to Junk in their business mailboxes - but they do know they’d better get on it or their messages to clients might go to Junk.

[immibis]

SMTP already has the BDAT command where the size is sent first, and arbitrary bytes can be sent (unlike DATA).

SMTP already has versioning through extensions.

If you're banning an IP for exceeding a processing resource limit please keep the ban short. Presumably you can afford to process the first 128KB of one bad message per six hours, for instance. There should be no need to make a month-long or permanent ban, and these just hurt interoperability if the sender realizes their problem and fixes it, or if the address is reallocated.

Trying to limit data between the hello and the email data is futile, since the attacker can just flood you with random packets no matter whether you told them to stop (closed the connection) or not. You can only limit things you have control over, mostly your own memory usage, and how much data is accepted into more expensive processing stages.

[justsomehnguy]

> 128KB of one bad message per six hours, for instance. There should be no need to make a month-long or permanent ban

As someone who saw the actual bruteforce attempts, most bots abandon any attempts after an hour or two. Resources are cheap but even for spammers (almost unlimited resources) futile attempts are costly.

[aembleton]

> I can assure you that random guy next desk will not care about your "this is a top-posting-thread" header and bottom post there.

We should move away from having a single mutable body for email. It should be a series of immutable messages that reference the message that it is replying to. Each message can contain a hash signed by the private key for the domain that wrote it. Then when you write your message it just gets appended to this chain.

How it is shown is up to the email client so that it can be done in the best way for the user.

[SassyBird]

What you’re describing is already possible with email as it is, using the In-Reply-To header or whatever its name was. No need for cryptographic signatures. The only issue is that common mail clients still automatically quote the whole message being replied to for no good reason. It should work like it used to on phpbb forums: no quote by default, quote selected part if text is selected.

[leni536]

> The only issue is that common mail clients still automatically quote the whole message being replied to for no good reason.

Here is a good reason: In-Reply-To is a reference, not content. The recipient(s) of your message might not have that email.

Also including the quote is a default. The sender can edit it, splice responses into it and remove irrelevant parts of it. Admittedly quoting norms are in shambles though for various reasons.

[wizzwizz4]

> Each message can contain a hash signed by the private key for the domain that wrote it.

Me being able to prove that I wrote something is good. Other people being able to prove that I wrote something… it's good under many circumstances, but not in general.

[jenny91]

What about responding inline to parts of a message?

[gjsman-1000]

We do it like Hacker News. It's just another message, with > indicators. Globally, inline replies are A. Rare and B. Often used with prank intent (i.e. you can make it look like you're replying to something they didn't say).

[gray_-_wolf]

Not sure about globally, but on most mailing lists I read they are used quite often.