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Re: [ietf-smtp] Quoted-Printable-8bit

2021-03-30 09:07:10
On 30/03/2021 13:07, Hector Santos wrote:
On 3/30/2021 7:31 AM, Jeremy Harris wrote:

Summary: 8BITMIME has been irrelevant for years.
You send it.

+1,   we totally assume 8 bit!!  We have nothing that needs 7 bit masking.

We dont either, but RFC 6152 (written in 2011) has the text that [if the server does not advertise 8BITMIME support]:

   the client SMTP must not, under any circumstances, attempt to
   transfer a content that contains characters outside of the US-ASCII
   octet range (hex 00-7F)."

This seemed quite a strongly worded requirement, so we'd made the decision that that requirement made it too complicated to handle gracefully, and as it was so strongly worded, we'd better not ignore it.

But, if people are ignoring that requirement, it's actually interesting. Not because people aren't following the standards, but that suggests that 8BITMIME isn't actually that widely used...

I'd assumed that the reason we very rarely see incoming "content-transfer-encoding: 8bit" MIME messages is because we don't advertise that we support 8BITMIME so most senders were transcoding them as RFC 6152 requires. But, if servers are just sending them in the 8-bit form anyway, I'd expect to see loads of 'cte: 8bit' messages, but the vast majority of '8 bit' messages we receive are QP encoded with a few Base64 encoded. A few (single digit percentage) are 'cte: 8bit', mostly spam, with some transactional messages from the same few senders.

Paul Smith Computer Services
support(_at_)pscs(_dot_)co(_dot_)uk - 01484 855800


Paul Smith Computer Services
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