Re: KMail encoding in base64

Sorry, for the late reply.

On Thursday 23 July 2009, Stefan Roese wrote:
> On Wednesday 22 July 2009 23:46:19 Ingo Klöcker wrote:
> > > > KMail uses certain heuristics to determine whether the message
> > > > should be base64 encoded or quoted-printable encoded. In my
> > > > experience, base64 is chosen if the message is pretty short and
> > > > contains a few non-ASCII characters (i.e. umlauts, accented
> > > > letters, etc.).
> > > >
> > > > > and how to prevent KMail from doing this?
> > > >
> > > > Why do you want to prevent KMail from doing so?
> > >
> > > Because it's not allowed to send such mails to some mailing lists
> > > (e.g. u- boot: http://www.denx.de/en/Software/MailingLists).
> > >
> > > So is there currently no chance to prevent this base64 encoding
> > > in KMail?
> >
> > No. (Except for the obvious "patch the source code and compile
> > yourself".)
>
> Heh. ;)
>
> > Unless the ratio of non-ASCII characters in the message is too high
> > KMail shouldn't use base64 encoding. So as workaround you could
> > always add a few lines of ASCII characters (maybe as footer) to
> > bring the ratio of non-ASCII below the threshold.
>
> I already have a footer in most of my mails (including the base64
> one, see below). I would really like to avoid adding even more of
> such text to my mails.
>
> > Or maybe there's a bug in the
> > calculation of the ratio. Can you send me a sample message?
>
> Sure, please find one attached.

Hmm. I copied the message text to a new message. KMail 1.9.10 (KDE 3.5) 
uses quoted-printable encoding. There is only one non-ASCII character 
in the message, but if quoted-printable encoding is used then all of 
the '=' in the footer need to be quoted-printable encoded as well. This 
makes the usage of quoted-printable encoding a bit more expensive, but 
using base64 encoding still is much more expensive. Quoted-printable 
encoded the text of the sample message weighs 1609 bytes. base64 
encoded it weighs 1759 bytes.


Conclusion:

a) The heuristic in KMail 1.12 deciding which encoding to use seems to 
be buggy. Please file a bug report for this.

b) Replacing '=' by '-' in your footer might fix your problem or make it 
much less likely to occur.


> Thanks for looking into this.

Welcome!


Regards,
Ingo

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