Cyrus 2.2?

John Alton Tamplin jtampli at
Fri May 9 16:00:06 EDT 2003

Christian Schulte wrote:

> That is, it contains ASCII-Characters > 127 ? So some client or 
> whatever introduced wrong header data because  there can only be 
> headers containing 7-bit characters and 8-bit data can only be 
> contained encoded as per RFC2047 in 7 bit representation ?

Correct.  The message header is constrained to contain only ASCII 
characters because the header is what is used to define the character 
set for the rest of the message.  RFC2047 gives a way to encode the data 
portions of the header in a self-contained format that is still ASCII to 
a mail client that doesn't understand RFC2047.

> We assume the character > 127 is in the configured default charset 
> which could be taken from LC_ environment and try to convert the 8 bit 
> data to a rfc2047 7bit representation leading to an incorrect 
> converted header if the default character set is not the correct one ? 
> How will you test against not converting to a wrong representation ?

Rather than taking the language from an environment variable, it would 
be configured in imapd.conf.  You can't test against it being 
incorrectly converted because there is no information to identify what 
character set was intended.  Presumably, if the rest of the message is 
MIME and has a character set you could assume the header is the same, 
but the mail clients I have seen that support MIME support the proper 
encoding of the headers.

> So we cannot mangle or reject messages any more which contain 8bit 
> header data not in the configured charset because we will convert them 
> to 7bit using another (maybe completely wrong) charset ?  I'll have to 
> read other rfcs than rfc2047 to understand it completely, I think!

The point is the message is already broken because it includes non-ASCII 
characters but no indication of what character set is in use.  The mail 
system administrator making a guess for a default is as good as the mail 
client making a guess and doesn't require storing non-compliant messages 
in the mail store.  The existing behavior in Cyrus is either to reject 
the message or mangle the offending characters into X.

John A. Tamplin                               Unix System Administrator
Emory University, School of Public Health     +1 404/727-9931

More information about the Info-cyrus mailing list