control characters and Util::clean_text()

[byron]

> >>Technically, you're not allowed anything that's not US-ASCII in email 
> >>headers, but that's another bug.
> >
> >Didn't this recently change? I believe umlauts and such characters are 
> >(since very very recently) allowed.
> 
> RFC2822 (April 2001) section 2.1 states:
> 
>    A message that is conformant with this standard is comprised of
>    characters with values in the range 1 through 127 and interpreted as
>    US-ASCII characters [ASCII].  For brevity, this document sometimes
>    refers to this range of characters as simply "US-ASCII characters".
> 
> That RFC is not listed as being obsoleted or updated by any other RFCs yet.
> 
> The only legal way to get around that is by base64 or quoted-printable 
> encoding the header values, which is described in RFC2045 and RFC2231.

RFC1652 (July 1994) introduced 8bit MIME.

RFC3030 (December 2000) introduced BDAT (binary version of DATA)
[obsoletes RFC1830 - August 1995].


-b

begin-base64 644 signature.gif
R0lGODlhbQAHAIAAAABPo////ywAAAAAbQAHAAACfAxuGAnch+Bibkn7FL1p
XgVl4Ig1jjlZRoqybgun2Cur5uOunq7u/Ipq7WIyIc7XG9JquEgumPzdlhTf
h0O83kDJaXEm8mRHwXKJy5sac7qYOpT+gtv0n+0ujQOfdqh16caWt0foBViH
N1PRMXimiLUGt3ElVimlgbllWAAAOw==
====