KMail thread view

Kevin Krammer kevin.krammer at
Fri Jan 29 13:10:56 GMT 2010

On Friday, 2010-01-29, Edgar Kalkowski wrote:
> Hi everyone!
> I very much like the new KMail of KDE 4 and very much enjoy the threaded
>  view especially when reading mailing lists. However sometimes KMail fails
>  to recognize that some message is a response to a previous message. Can
>  this be because some people change the subject of mails they respond to to
>  “[Re: Subject]” instead of the usual “Re: Subject”?
> Or what is it that KMail uses to build up the threaded view?

The first and most important threading information are message headers for 
that very purpose.

For example if you look at this mail's "source" (e.g. by pressing the V key), 
you'll find two such headers: references and in-reply-to, containing the 
message ID of your mail.

KMail can therefore easily figure out that this is a reply to you mail, 
independent of whether I change the subject or not.

However, some email clients don't do this properly, e.g. file to set the 
headers correctly or not at all.

In such situations KMail will try to work around the other client's brokeness 
by guessing threading through hints like subject and known subject prefixes 
like "Re:"

Since guessing is never the same as knowing, there can be situations where 
KMail guess is wrong.

It might be possible to fine tune this behavior somewhat, e.g. which prefixes 
are understood when parsing subjects.

Kevin Krammer, KDE developer, xdg-utils developer
KDE user support, developer mentoring
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