On Mon, 26 Oct 1998, Ashley Yakeley wrote:
...but I'd like to point out that quoted-printable may not be necessary
to encode non-US-ASCII, given UTF-7.
The question is, which is better for the existing (international) base of
installed users as would be recipients: using qp (at the transport
level), or using UTF-7 (at the content-type level)?
NO! NO! ARRRGGHGGHGHH! Don't use UTF-7 in email.
Am I going to have to dust off the draft on "UTF-7 in MIME considered
UTF-7 has the following problems:
* far worse backwards compatibility than quoted-printable. Some people
hate MIME due to what they consider "quoted-unreadable". If you use
UTF-7, there will be lots of people who will start hating Unicode as a
* Massive layering violation -- it uses a content-transfer-encoding in a
character set, thus forcing base64 code in multiple layers of code.
* Double-encoding. UTF-7 is base64-encoded UTF-16 which is itself an
encoding of UCS-4. Bletch.
* Searches are impossible without decoding UTF-7. (and it can't be mapped
internally on a signed message, since there's no canonical form).
* The uptake of the 8BITMIME SMTP extension has been excellent. This
means that unencoded UTF-8 with CTE 8-bit is usually possible. UTF-8
doesn't have double-encoding or searching problems.
I could go on. People who generate UTF-7 are doing a great disservice to
the Internet, IMHO.