control characters and Util::clean_text()

[Dennis Melentyev]

Wed, 21/12/2005 в 22:30 -0500, Mick Weiss wrote:
> David Miller wrote:
> 
> > ...
> > 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.
I'm not aware of any new RFC's on this, but I can state, that most
mailers (MTA/MSA/IMAP/POP3) allow 8-bit headers. The only known IMAP
server explicitly replacing 8-bit chars to 'X' is courier-imap.
So, technically, there is no problem to transmit 8-bit headers but this
will violate RFC's.
As Dave and I told earlier - the simplest way is to base64/qp encode ALL
e-Mail headers.