Re: [ietf-smtp] [Proposal] confusing parts of the mail system, was 250-MARKDOWN

Brandon Long <blong@google.com> Wed, 09 January 2019 22:06 UTC

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From: Brandon Long <blong@google.com>
Date: Wed, 09 Jan 2019 14:05:49 -0800
Message-ID: <CABa8R6vM6z5YZzv0L-hTsYFDuqjfEPDLyT31w0J_FchpXwsy-Q@mail.gmail.com>
To: Viruthagiri Thirumavalavan <giri@dombox.org>
Cc: John Levine <johnl@taugh.com>, ietf-smtp <ietf-smtp@ietf.org>
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Subject: Re: [ietf-smtp] [Proposal] confusing parts of the mail system, was 250-MARKDOWN
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I think the distinction isn't as strict as John puts it, though that
doesn't mean the proposal is correct either.

Today's MTAs often have to do a lot of message body handling for
spam/av/malware/phishing, especially if they want to be able to reject bad
messages at SMTP time to prevent backscatter.

I'd also point out that there are multiple SMTP extensions for negotiating
the format of the SMTP data (SMTPUTF8, 8BITMIME, BINARY), though those
typically apply to the full format of the data portion and not just
specific parts of it.

That said, late transformations or transformations in hops have been
offered in the past, and now interact poorly with the digital signatures
present in DKIM/ARC/SMIME, and so should be avoided.  Downgrading also
failed in UTF8SMTP, as another example.

Frankly, I don't see text/markdown replacing text/plain or text/html as the
primary message content any time soon, it doesn't really solve a problem
people have.  Obviously there should be a mime type for it, but most MUAs
provide a WYSIWYG interface based on HTML these days, and have for years,
they're not chomping at the bit to hand craft formatted responses.

Brandon

On Wed, Jan 9, 2019 at 6:56 AM Viruthagiri Thirumavalavan <giri@dombox.org>
wrote:

> Ok Thanks John.
>
> I'll take a look.
>
> On Wed, Jan 9, 2019 at 8:05 PM John Levine <johnl@taugh.com> wrote:
>
>> In article <
>> CAOEezJTxTN9x_JFXgLidj9k8NVgFTRyqyQc4Aak8UEQuvjiM0w@mail.gmail.com> you
>> write:
>> >-=-=-=-=-=-
>> >
>> >You are right. I was worried that receiving server would not recognize
>> >"text/markdown" as a media type since it was registered recently in the
>> >RFC. So if a server started to recognize that as media type, I thought
>> they
>> >should do that via SMTP extension.
>>
>> My mail server doesn't support or understand any media types at all.
>> MIME and
>> media types are all handled in the MUA.
>>
>> Please review RFC 5598, the Internet Mail Architecture.  The mail
>> server that advertises EHLO keywords is an MTA.  MIME types are
>> handled in the MUA.
>>
>> Also, practically, every modern MUA handles HTML now.  If you want to use
>> markdown, adjust your MUA so it translates your markdown into text/html
>> and sends that.  There are dozens of markdown->html translators so this
>> is just splicing together code that already exists.
>>
>> R's,
>> John
>>
>
>
> --
> Best Regards,
>
> Viruthagiri Thirumavalavan
> Dombox, Inc.
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