What's up with all those equals signs anyway?

15 hours ago (lars.ingebrigtsen.no)

For context, this is the Lars Ingebrigtsen who wrote the manual for Gnus[0], a common Emacs package for reading email and Usenet. It’s clever, funny, and wildly informative. Lars has probably forgotten more about email parsing than 99% of us here will ever have learned.

The manual itself says[1]:

> Often when I read the manual, I think that we should take a collection up to have Lars psycho-analysed.

0: https://www.gnu.org/software/emacs/manual/html_mono/gnus.htm...

1: https://www.gnus.org/manual.html

  • Not only the manual, but Gnus itself. I remember this guy from the university (UiO) when he started working on Gnus. He was a small celebrity among us informatics students, and we all used Emacs and Gnus, of course.

    • I'd forgotten that! Yeah, I believe Lars also wrote a huge chunk of the current Gnus. I stopped using it a while back and maybe someone else came along and rewrote it again, replacing all his code, but I don't think that's the case.

      Gnus was absolutely delightful back in the day. I moved on around the time I had to start writing non-plaintext emails for work reasons. It's also handy to be using the same general email apps and systems as 99.99% of the rest of the world. I still have a soft spot in my heart for it.

      PS: Also, I have no idea whatsoever why someone would downvote you for that. Weird.

The real punchline is that this is a perfect example of "just enough knowledge to be dangerous." Whoever processed these emails knew enough to know emails aren't plain text, but not enough to know that quoted-printable decoding isn't something you hand-roll with find-and-replace. It's the same class of bug as manually parsing HTML with regex, it works right up until it doesn't, and then you get congressional evidence full of mystery equals signs.

  • > It's the same class of bug as manually parsing HTML with regex, it works right up until it doesn't

    I'm sure you already know this one, but for anyone else reading this I can share my favourite StackOverflow answer of all time: https://stackoverflow.com/a/1732454

    • I prefer the question about CPU pipelines that gets explained using a railroad switch as example. That one does a decent job of answering the question instead of going of on a, how to best put it, mentally deranged one page rant about regexes with the lazy throw away line at the end being the only thing that makes it qualify as an answer at all.

      9 replies →

    • It took me years to notice, but did you catch that the answer actually subtly misinterprets what the question is asking for?

      Guy (in my reading) appears to talk about matching an entire HTML document with regex. Indeed, that is not possible due to the grammars involved. But that is not what was being asked.

      What was being asked is whether the individual HTML tags can be parsed via regex. And to my understanding those are very much workable, and there's no grammar capability mismatch either.

      7 replies →

    • I know this is grumpy but this I’ve never liked this answer. It is a perfect encapsulation of the elitism in the SO community—if you’re new, your questions are closed and your answers are edited and downvoted. Meanwhile this is tolerated only because it’s posted by a member with high rep and username recognition.

      5 replies →

    • Funny how differently people can perceive things. That's my least favorite SO answer of all time, and I cringe every time I see it.

      It's a very bad answer. First of all, processing HTML with regex can be perfectly acceptable depending on what you're trying to do. Yes, this doesn't include full-blown "parsing" of arbitrary HTML, but there are plenty of ways in which you might want to process or transform HTML that either don't require producing a parse tree, don't require perfect accuracy, or are operating on HTML whose structure is constrained and known in advance. Second, it doesn't even attempt to explain to OP why parsing arbitrary HTML with regex is impossible or poorly-advised.

      The OP didn't want his post to be taken over by someone hamming it up with an attempt at creative writing. He wanted a useful answer. Yes, this answer is "quirky" and "whimsical" and "fun" but I read those as euphemisms for "trying to conscript unwilling victims into your personal sense of nerd-humor".

      4 replies →

  • And because the output still looks mostly readable, nobody questions it until years later when it's suddenly evidence in front of Congress

> We see that that’s a quite a long line. Mail servers don’t like that

Why do mail server care about how long a line is? Why don't they just let the client reading the mail worry about wrapping the lines?

  • SMTP is a line–based protocol, including the part that transfers the message body

    The server needs to parse the message headers, so it can't be an opaque blob. If the client uses IMAP, the server needs to fully parse the message. The only alternative is POP3, where the client downloads all messages as blobs and you can only read your email from one location, which made sense in the year 2000 but not now when everyone has several devices.

  • Mails are (or used to be) processed line-by-line, typically using fixed-length buffers. This avoids dynamic memory allocation and having to write a streaming parser. RFC 821 finally limited the line length to at most 1000 bytes.

    Given a mechanism for soft line breaks, breaking already at below 80 characters would increase compatibility with older mail software and be more convenient when listing the raw email in a terminal.

    This is also why MIME Base64 typically inserts line breaks after 76 characters.

    • In early days, many/most people also read their email on terminals (or printers) with 80-column lines, so breaking lines at 72-ish was considered good email etiquette (to allow for later quoting prefix ">" without exceeding 80 characters).

      1 reply →

  • I don't think kids today realize how little memory we had when SMTP was designed.

    For example, the PDP-11 (early 1970s), which was shared among dozens of concurrent users, had 512 kilobytes of RAM. The VAX-11 (late 1970s) might have as much as 2 megabytes.

    Programmers were literally counting bytes to write programs.

    • I assure you we were not, at least it wasn’t really necessary. Virtual Memory is a powerful drug.

  • This is how email work(ed) over smtp. When each command was sent it would get a '200'-class message (success) or 400/500-class message (failure). Sound familiar?

    telnet smtp.mailserver.com 25

    HELO

    MAIL FROM: me@foo.com

    RCPT TO: you@bar.com

    DATA

    blah blah blah

    how's it going?

    talk to you later!

    .

    QUIT

    • For anyone who wants to try this against a modern server:

          openssl s_client -connect smtp.mailserver.com:smtps -crlf
          220 smtp.mailserver.com ESMTP Postfix (Debian/GNU)
          EHLO example.com
          250-smtp.mailserver.com
          250-PIPELINING
          250-SIZE 10240000
          250-VRFY
          250-ETRN
          250-AUTH PLAIN LOGIN
          250-ENHANCEDSTATUSCODES
          250-8BITMIME
          250-DSN
          250-SMTPUTF8
          250 CHUNKING
      
          MAIL FROM:me@example.com
          250 2.1.0 Ok
      
          RCPT TO:postmaster
          250 2.1.5 Ok
      
          DATA
          354 End data with <CR><LF>.<CR><LF>
      
          Hi
          .
          250 2.0.0 Ok: queued as BADA579CCB
      
          QUIT
          221 2.0.0 Bye

  • Back in 80s-90s it was common to use static buffers to simplify implementation - you allocate a fixed size buffer and reject a message if it has a line longer than the buffer size. SMTP RFC specifies 1000 symbols limit (including \r\n) but it's common to wrap around 87 symbols so it is easy to examine source (on a small screen).

  • The simplest reason: Mail servers have long had features which will send the mail client a substring of the text content without transferring the entire thing. Like the GMail inbox view, before you open any one message.

    I suspect this is relevant because Quoted Printable was only a useful encoding for MIME types like text and HTML (the human readable email body), not binary (eg. Attachments, images, videos). Mail servers (if they want) can effectively treat the binary types as an opaque blob, while the text types can be read for more efficient transfer of message listings to the client.

  • As far as I can remember, most mail servers were fairly sane about that sort of thing, even back in the 90’s when this stuff was introduced. However, there were always these more or less motivated fears about some server somewhere running on some ancient IBM hardware using EBCDIC encoding and truncating everything to 72 characters because its model of the world was based on punched cards. So standards were written to handle all those bizarre systems. And I am sure that there is someone on HN who actually used one of those servers...

  • RFC822 explicitly says it is for readability on systems with simple display software. Given that the protocol is from 1982 and systems back then had between 4 and 16kb RAM in total it might have made sense to give the lower end thin client systems of the day something preprocessed.

    • Also it is an easy way to stop a denial of service attack. If you let an infinite amount in that field. I can remotely overflow your system memory. The mail system can just error out and hang up on the person trying the attack instead of crashing out.

      1 reply →

    • You could expect a lot more (512kB, 1MB, 2MB) in an internet-connected machine running Unix or VMS.

  • Keep in mind that in ye olden days, email was not a worldwide communication method. It was more typical for it to be an internal-only mail system, running on whatever legacy mainframe your org had, and working within whatever constraints that forced. So in the 90s when the internet began to expand, and email to external organizations became a bigger thing, you were just as concerned with compatibility with all those legacy terminal-based mail programs, which led to different choices when engineering the systems.

I wrote my own email archiving software. The hardest part was dealing with all the weird edge cases in my 20+ year collection of .eml files. For being so simple conceptually, email is surprisingly complicated.

  • Email is one of those cursed standards where the committee wasn't building a protocol from scratch, but rather trying to build a universal standard by gluing together all of the independently developed existing systems in some way that might allow them to interoperate. Verifying that a string a user has typed is a valid email address is close to impossible short of just throwing up your hands and allowing anything with a @ somewhere in it.

    • Email is one of the very few success cases of the xkcd Standards meme: https://xkcd.com/927/ - and it's due to practicality and ingenuity on the part of people who made very creative parsers and placed real-world understanding behind every word of the early RFCs.

      Without a unified email standard, the world would look incredibly different today, especially as it bootstrapped open communication between different countries and institutions in developing every protocol since.

  • I wrote a console-based mail client, which was 25% C++ and 75% Lua for defining the UI and the processing.

    It never got too popular, but I had users for a few years and I can honestly say MIME was the bane of my life for most of those years.

    • Indeed. A big chunk of my email parser deals with missing or incorrect content headers. Most of the rest attempts to sensibly interpret the infinite combinations of parts found in multipart (and single-part!) emails.

The most interesting thing to me wasn't the equals signs, which I knew are from quoted-printable, but the fact that when an equals sign appears, a letter that should have been preceding or following it is missing. It's as if an off-by-one error has occurred, where instead of getting rid of the equals sign, it's gotten rid of part of the actual text. Perhaps the CRLF/LF thing is part of it.

I'm just wondering why this problem shows up now. Why do lots of people suddenly post their old emails with a defective QP decoder?

> For some reason or other, people have been posting a lot of excerpts from old emails on Twitter over the last few days.

On the risk of having missed the latest meme or social media drama, but does anyone know what this "some reason or other" is?

Edit: Question answered.

  • [flagged]

    • Of course the Epstein files are serious.

      But not everybody has every single global development / news event IVed into their veins. Many of us just don’t keep updated on global news such that we may not be aware of an event that happened in the last 3 days.

      Important news tends to get to me eventually. And there is usually nothing I can do about something personally anyway (at least within a short time horizon), so there is really very little value in trying to stay informed of the absolute latest developments. The signal to noise ratio is far too low, and it also induces a bunch of unnecessary anxiety and stress.

      So yes, believe it or not very many people are unaware of this.

> So what’s happened here? Well, whoever collected these emails first converted from CRLF (i.e., “Windows” line ending coding) to “NL” (i.e., “Unix” line ending coding). This is pretty normal if you want to deal with email. But you then have one byte fewer:

I think there is a second possible conclusion, which is that the transformation happened historically. Everyone assumes these emails are an exact dump from Gmail, but isn't it possible that Epstein was syncing emails from Gmail to a third party mail server?

Since the Stackoverflow post details the exact situation in 2011, I think we should be open to the idea that we're seeing data collected from a secondary mail server, not Gmail directly.

Do we have anything to discount this?

(If I'm not mistaken, I think you can also see the "=" issue simply by applying the Quoted-Printable encoding twice, not just by mishandling the line-endings, which also makes me think two mail servers. It also explains why the "=" symbol is retained.)

  • In one of the email PDFs I saw an XML plist with some metadata that looked like it was from Apple's Mail.app, so these might be extracted from whatever internal format that uses.

  • What happened here is what always happens with all printed and digital material that goes through some evidentiary process.

    The shot-callers demand the material, which is a task fobbed off onto some nobody intern who doesn't matter (deliberately, because the lawyers and career LEOs don't want any "officer of the court" or other "party" to put eyes on things they might need to deny knowing about later.) They use only the most primitive, mechanical method possible, with little to no discretion. The collected mass of mangled junk is then shipped to whoever, either in boxes or on CD-ROM/DVD (yes, still) or something. Then, the reverse process is done, equally badly, again by low-level staff, also with zero discretion and little to no technical knowledge or ability, for exactly the same reasons, to get the material into some form suitable for filing or whatever.

    Through all of this, the subtle details of data formats and encodings are utterly lost, and the legal archive fills with mangled garbage like raw quoted-printable emails. The parties involved have other priorities, such as minimizing the number of people involved in the process, and tight control over the number of copies created. Their instinct is not to bring in a bunch of clever folk that might make the work product come out better, because "better" for them is different than "better" for Twitter or Facebook. Also, these disclosures are inevitably and invariably challenged by time: the obligation to provide one thing or another is fought to the last possible minute, and when the word does finally go out there is next to no time to piddle around with details.

    In the Epstein case, the disclosures were done years ago, the original source material (computers, accounts, file systems, etc.) have all long since been (deliberately) destroyed, and what the feds have is the shrapnel we see today.

  • When they process these emails, it's fairly common to import everything into a MS Outlook PST file (using whatever buggy tool). That's probably why these look like Outlook printouts even though its Yahoo mail or etc.

  • Yeah, I wouldn't bet on this being a single bad Gmail export; it smells much more like the accumulated scars of multiple mail systems doing "helpful" things to the same messages over time

I'd like a good .eml viewer that undoes the quoted printable transformation for the contained plain and html text. useful for mails downloaded from Outlook.

I love how HN always floats up the answers to questions that were in my mind, without occupying my mind.

I, too, was reading about the new Epstein files, wondering what text artifact was causing things to look like that.

  • Me too. I first assumced it was an OCR error, then remembered they were emails and wouldn't need to go through OCR. Then I thought that the US Government is exactly the kind of place to print out millions of emails only to scan them back in again.

    I'm glad to know the real reason!

    • I just want to add that I would expect the exact same thing from the German government. Glad to see we're not all that different

CLRF vs LF strikes again. Partly at least.

I wonder why even have a max line length limit in the first place? I.e. is this for a technical reason or just display related?

  • Wait, now we have to deal with Carriage Line Return Feeds too?

    I wonder if the person who had the idea of virtualizing the typewriter carriage knew how much trouble they would cause over time.

    • Yeah, and using two bytes for a single line termination (or separation or whatever)? Why make things more complicated and take more space at the same time?

      8 replies →

  • I haven't seen them other than in the submission - but if the length matches up it may be that they were processed from raw email, the RFC defines a length to wrap at.

    Edit: yes I think that's most likely what it is (and it's SHOULD 78ch; MUST 998ch) - I was forgetting that it also specifies the CRLF usage, it's not (necessarily) related to Windows at all here as described in TFA.

    Here it is in my 'notmuch-more' email lib: https://github.com/OJFord/amail/blob/8904c91de6dfb5cba2b279f...

    • > it's not (necessarily) related to Windows at all here as described in TFA.

      The article doesn't claim that it's Windows related. The article is very clear in explaining that the spec requires =CRLF (3 characters), then mentions (in passing) that CRLF is the typical line ending on Windows, then speculates that someone replaced the two characters CRLF with a one character new line, as on Unix or other OSs.

      1 reply →

  • I am just wondering how it is good idea for a sever to insert some characters into user's input. If a collegue were to propose this, i d laugh in his face

    It's just sp hacky i cant belive it's a real life's solution

    • “Insert characters”?

      Consider converting the original text (maintaining the author’s original line wrapping and indentation) to base64. Has anything been “inserted” into the text? I would suggest not. It has been encoded.

      Now consider an encoding that leaves most of the text readable, translates some things based on a line length limit, and some other things based on transport limitations (e.g. passing through 7-bit systems.) As long as one follows the correct decoding rules, the original will remain intact - nothing “inserted.” The problem is someone just knowledgeable enough to be aware that email is human readable but not aware of the proper decoding has attempted to “clean up” the email for sharing.

      2 replies →

    • It's called escaping, and almost every protocol has it. HN must convert the & symbol to &amp; for displaying in HTML. Many wire protocols like SATA or Ethernet must insert a 1 after a certain number of consecutive 0s to maintain electrical balance. Don't remember which ones — don't quote me that it's SATA and Ethernet.

      1 reply →

Dear GNU's: rewrite the fetching core so it gets performant enough to not crawl under 10000 headers from either usenet or Email. No, even native compilation is fast enough.

My main takeaway from this article, is that I want to know what happened to the modified pigs with non-cloven hoofs

    cat title | sed 's/anyway/in email/'

would save a click for those already familiar with =20 etc.

Great. Can't wait for equal signs to be the next (((whatever this is))). Maybe it's a secret code. j/k

On a side note: There are actually products marketed as kosher bacon (it's usually beef or turkey). And secular Jews frequently make jokes like this about our kosher bros who aren't allowed to eat the real stuff for some dumb reason like it has too many toes.

"It’s a fascinating case of 'Abstraction Leak'.

We’ve become so accustomed to modern libraries handling encoding transparently that when raw data surfaces (like in these dumps), we often lack the 'Digital Archeology' skills to recognize basic Quoted-Printable.

These artifacts (=20, =3D) are effectively fossils of the transport layer. It’s a stark reminder that underneath our modern AI/React/JSON world, the internet is still largely held together by 7-bit ASCII constraints and protocols from the 1980s.

TLDR "=\r\n" was converted to "=\n"

Could be worsened by inaccurate optical character recognition in some cases.

Back in those days optical scanners were still used.

Rock dots? You mean diacritics? Yeah someone invented them: the ancient Greeks, idiöt.