I’m one of the moderators on a large email discussion list. Quite often when we receive a message for approval it might be full of what I can only call “funny characters” or character sequences. They always begin with an equals sign, though. For example, things like =0D=0A and =3D appear throughout the message.
But wait, this gets even more odd. If we allow such a message to go through to our list, most members who receive the messages individually don’t see this oddness; messages look just fine to them. And yet, members who receive these messages in a periodic digest see the same funny characters as we moderators do.
What’s up what that?
You’d think that with plain-text email having been around for as long as it has, issues like this would have been resolved by now.
The problem is that there’s “plain text” email, and then there’s “plain text” email. That’s correct — not all “plain text” is created equal.
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When you see something like =3D, what you’re seeing is a single character of “quoted-printable” encoding.
“=3D” is, in fact, an equal sign. =0D is a Carriage Return (CR), =0A is a Line Feed (LF), and =0D=0A is a CRLF combination. CR, LF, and CRLF are all used to indicate the end of a line of text in plain text emails. In fact, any character can be represented as a three character “=” sequence in quoted-printable. “=41=73=6B=20=4C=65=6F=21”, for example, is “Ask Leo!” in full quoted-printable encoding.
Quoted-printable is one of several encodings used to get around the fact that not all mail software (and in the past, not all network transports) can handle what are called “non-printable” characters, or certain types of non-alphanumeric characters.
CR and LF, for example, don’t cause anything to be displayed; they just “mean something”: the end of a line. That’s why they’re called “non-printable”.
Non-printable characters in email messages can confuse some email software, particularly older, legacy systems. The work-around is to represent them in a way that doesn’t confuse the old mailers.
How mail programs identify quoted-printable
When an email message uses quoted-printable, one of the hidden headers — the information you don’t normally see — explicitly says so.
If you’re seeing the quoted-printable characters in their quoted-printable form, that header is either missing, malformed, or it’s been overlooked.
In the case of your mailing list, the approvals are likely arriving in some kind of “raw” form. Your mailing list software has probably removed or overridden the header information. As a result, your mail program doesn’t know that it should decode the encoded characters. It sees it as unencoded plain text email and displays it as-is.
Digests are special
A digest is a collection of emails bundled into a single message. Rather than getting a number of individual messages, many mailing lists allow you to get a digest version instead. It arrives less frequently, but includes multiple messages instead of just one.
The “problem” is that not all messages are encoded using “quoted-printable”.
In theory, I suppose, the mailing list software could try to normalize: understand the encoding used and convert it to a single standard which it would then use to send the digest. Since I’ve never seen that happen, I assume there’s some reason this can’t be done.
As a result, all messages are collected into each digest in raw form.
What to do
If you’re a list owner or moderator, there’s not much you can do for the list itself.
As a recipient, you may have some options. Some mailing list software has multiple types of digesting, some of which may handle the situation better. One list that I’m on, for example, creates a digest that contains the individual messages as “.eml” attachments, which preserve each message in its original form. Unfortunately, it’s more difficult to read, as you need to open each attachment individually.
Fortunately, in recent years mail servers and software have progressed to the point where this isn’t the issue it once was. Unfortunately, though, it still remains in some corners of the email world, particularly with older mailing-list software.