XPost: alt.free.newsservers, alt.free.nntp

Looking at these three lines, why bother with the Mime-version when I can't find anyone who doesn't use Mime version 1.0 (is there another version)?

What's the difference between the Content-Transfer-Encoding: of 7bit, 8bit
& quoted-printable? (and please don't say 1 bit as that's not funny)

Is there a good reason to use a character set that isn't ISO-8859-1?
(Most seem to use "us-ascii", "UTF-*" & "ISO-8859-1".)

Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

MIME-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit

MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit

MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit

Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit

MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable

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XPost: alt.free.newsservers

cutting a non-existant newsgroup from the crosspost

Peter <occassionally-confused@nospam.co.uk> wrote:

Looking at these three lines, why bother with the Mime-version when I can't >find anyone who doesn't use Mime version 1.0 (is there another version)?

It's simply there in case the protocol were extended.

What's the difference between the Content-Transfer-Encoding: of 7bit, 8bit
& quoted-printable? (and please don't say 1 bit as that's not funny)

7 and 8 aren't encoded at all. You'll have to look up QP; there's also
BASE64 encoding.

Is there a good reason to use a character set that isn't ISO-8859-1?
(Most seem to use "us-ascii", "UTF-*" & "ISO-8859-1".)

ASCII is default. Not all languages are served by the Latin-1 character
set, so there are plenty of other choices. UTF-8 covers all.

. . .

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XPost: alt.free.newsservers, alt.free.nntp

[Please do not mail me a copy of your followup]

Peter <occassionally-confused@nospam.co.uk> spake the secret code <u2a2p5$17h7q$1@dont-email.me> thusly:

Looking at these three lines, why bother with the Mime-version when I can't >find anyone who doesn't use Mime version 1.0 (is there another version)?

What's the difference between the Content-Transfer-Encoding: of 7bit, 8bit
& quoted-printable? (and please don't say 1 bit as that's not funny)

Is there a good reason to use a character set that isn't ISO-8859-1?
(Most seem to use "us-ascii", "UTF-*" & "ISO-8859-1".)

All your questions are answered in detail by the RFCs that cover MIME;
start with the wikipenis(TM) article: <https://en.wikipedia.org/wiki/MIME>
--
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The Terminals Wiki <http://terminals-wiki.org>
The Computer Graphics Museum <http://computergraphicsmuseum.org>
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Peter wrote:

Looking at these three lines, why bother with the Mime-version when I can't find anyone who doesn't use Mime version 1.0 (is there another version)?

No, but RFC 2049 specifies in section 2: <https://datatracker.ietf.org/doc/html/rfc2049#section-2>
|
| 2. MIME Conformance
|
| [...]
| A mail user agent that is MIME-conformant MUST:
|
| (1) Always generate a "MIME-Version: 1.0" header field in
| any message it creates.

Since RFC 5536 this requirement applies to Usenet too:
|
| 2.3. MIME Conformance
|
| User agents MUST meet the definition of MIME conformance in
| [RFC2049] and MUST also support [RFC2231].

What's the difference between the Content-Transfer-Encoding: of 7bit, 8bit
& quoted-printable? (and please don't say 1 bit as that's not funny)

They are just labels to indicate whether the encoding of the body needs
an 8-bit transport protocol or not.

"7bit" is the default and needs no declaration.

Note that there are non-ASCII encodings that don't need an 8-bit clean transport protocol (e.g. "UTF-7" or "ISO-2022-JP").

Is there a good reason to use a character set that isn't ISO-8859-1?
(Most seem to use "us-ascii", "UTF-*" & "ISO-8859-1".)

"US-ASCII", "ISO-8859-1" and "UTF-8" are supersets of each other
(codepoints are mapped 1:1 to the range up to U+007F, and to the range
up to U+00FF respectively, in Unicode).

This means that an Unicode UTF can be directly applied to "ISO-8859-1" codepoints (no mapping table is required). If Unicode data is received
and does not contain codepoints beyond U+00FF, it can be converted to "ISO-8859-1" by decoding the UTF (again no mapping table is required).

Today in general "UTF-8" should be preferred if "US-ASCII" is not
sufficient. For Usenet a fallback to "ISO-8859-1" can be useful because
many old newsreaders with MIME capability have problems with Unicode
(work better with 8-bit encodings).


[Xpost reduced]

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On Wed, 26 Apr 2023 03:37:52 +0100, Peter wrote:

Looking at these three lines, why bother with the Mime-version when I can't find anyone who doesn't use Mime version 1.0 (is there another version)?

The presence or absence of this header indicates whether the message
does or does not support the Multipurpose Internet Mail Extensions
(MIME). See RFC1521 section 3 or RFC2045 section 4.

You will be able to find messages which do not have a Mime-version
header, as well as messages which do have one.

____
REFERENCES:

RFC1521 section 3 : <https://www.rfc-editor.org/rfc/rfc1521#section-3>
RFC2045 section 4 : <https://www.rfc-editor.org/rfc/rfc2045#section-4>


--
Kind regards
Ralph

ζητεῖτε καὶ εὑρήσετε

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XPost: alt.free.newsservers, alt.free.nntp

In news.software.nntp Peter <occassionally-confused@nospam.co.uk> wrote:

Looking at these three lines, why bother with the Mime-version when I can't find anyone who doesn't use Mime version 1.0 (is there another version)?

When I experimented with it (a long time ago), one newsreader (I'm not
sure now, but it might have been alpine) ignored Content-Type when
Mime-Version was not specified. It made sense, as presence of Mime-Version
says that the message is MIME-compliant.

What's the difference between the Content-Transfer-Encoding: of 7bit, 8bit
& quoted-printable? (and please don't say 1 bit as that's not funny)

You can encode the content during transfer with various encoding schemes.

7bit means that there are no 8-bit characters in the content.

8-bit means that there are 8-bit characters and they are passed as is.
It's probably OK for all modern server implementations, as they're 8-bit
clean.

Quoted-Printable encoding quotes non-safe characters in printable form by changing them to three-character representation, where first character is
= (equal sign) and two following characters encode the problematic byte in
a hexadecimal form.

You might also encounter base64, which codes groups of three bytes (8-bit)
into groups of four 6-bit codes, represented by uppercase and lowercase letters, digits and some symbols -- basically, printable and safe stuff.

Is there a good reason to use a character set that isn't ISO-8859-1?
(Most seem to use "us-ascii", "UTF-*" & "ISO-8859-1".)

It might be used for historic reasons. On Polish groups you'll encounter,
apart from utf-8, also iso-8859-2 (and sometimes windows-1250).

Content-Type: text/plain; charset=UTF-8; format=flowed

...and format=flowed means that the message can be reformatted during
display. See: https://joeclark.org/ffaq.html

Adam

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