It appears that Paul Smith <paul(_at_)pscs(_dot_)co(_dot_)uk> said:
We dont either, but RFC 6152 (written in 2011) has the text that [if the
server does not advertise 8BITMIME support]:
"then 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 think you're right. If your user base speaks English, it is not
likely to be sending around a lot of text where 8BITMIME would help,
and binary data is all sent as base64 because as we have seen,
the 25% bloat hasn't been enough to invent something like quoted-unprintable.
For really large stuff, people use Dropbox and its competitors.
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