Re: [exim] need help with UTF-8 in Subject: header

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Author: Phil Pennock
Date:  
To: Dmitry Pryadko
CC: exim-users
Subject: Re: [exim] need help with UTF-8 in Subject: header
On 2008-06-17 at 20:23 +0400, Dmitry Pryadko wrote:
> I have a problem with bounces.
>
> Here's an example of 'bounced' message original Subject:
>
> Subject: Re: =?UTF-8?Q?[=D0=97=D0=B0=D1=8F=D0=B2=D0=BA=D0=B0:2008061010026081]_?=
>     =?UTF-8?Q?=D0=9F=D1=80=D0=BE=D0=B2=D0=B5=D1=80=D0=BA=D0=B0_?=
>     =?UTF-8?Q?=D0=B4=D0=BE=D1=81=D1=82=D0=B0=D0=B2=D0=BA=D0=B8_?=
>     =?UTF-8?Q?=D1=8D=D0=BB=D0=B5=D0=BA=D1=82=D1=80=D0=BE=D0=BD=D0=BD=D0=BE=D0=B9_?=
>     =?UTF-8?Q?=D0=BA=D0=BE=D1=80=D1=80=D0=B5=D1=81=D0=BF=D0=BE=D0=BD=D0=B4=D0=B5=D0=BD=D1=86=D0=B8=D0=B8._?=


Exim is being very carefully adherent to the MIME specification in
RFC2047 which places a maximum length on each encoded-word.

----------------------------8< cut here >8------------------------------
encoded-word = "=?" charset "?" encoding "?" encoded-text "?="
[...]
An 'encoded-word' may not be more than 75 characters long, including
'charset', 'encoding', 'encoded-text', and delimiters. If it is
desirable to encode more text than will fit in an 'encoded-word' of
75 characters, multiple 'encoded-word's (separated by CRLF SPACE) may
be used.
----------------------------8< cut here >8------------------------------

So the MIME decoder is skipping those long strings and adding them
literally.

Is the original text spam? (Sorry, I don't read Russian). If not, then
those are broken mail-clients. The question then is what should be done
about it.

If you set "check_rfc2047_length" false in Exim's main configuration,
the header will be decoded correctly; I would assume (but haven't
checked) that Exim would then re-encode things correctly as needed.

check_rfc2047_length = false

-Phil