Cyrus 2.2?

Christian Schulte cs at
Fri May 9 16:29:02 EDT 2003

John Alton Tamplin wrote:

> 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.
Such functionality can/should be integrated in the MTA then, I think! I 
tested sendmail's ability to do such things but got very strange results 
so that I turned that features off after a few weeks. Mainly 90% of all 
broken messages were not in my default iso-8859-15 charset and got 
converted to something unreadable! It lead to some clients showing 
totally crippled from or even subject headers where cyrus would have 
only printed single X characters...
Of course 99% of all broken messages are spam.  Installing  
spamassassin  lead to not getting that much broken messages any more...
My experiences with sendmail make me think that such a feature would not 
introduce anythink really usefull then and cyrus allready handles broken 
messages in an elegant way however!


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