> 1. Some form of tracking of "read messages", color changed or whatever.

I think a more Celeste-y way would be to autofile messages into a "read"
folder.  Then you can add a filter for this.

Especially if you are using my patches for a "filtering celeste", which
lets you specify multiple filters at once.  Unfortunately, there are no
negative filters right now, nor are there the general programmed filters
of before.  But the architecture certainly allows it.

I've been kinda waiting to get a stable base for Celeste before plunging
onward on anything.  There are a lot of loose changesets floating
around, I think.  There is some discussion of moving to an external
repository; I hope that happens, though I don't have time to work on it
myself.



> 2. Threading. Also, I have noticed that Celeste doesn't send
> "in-reply-to" 

It does use "References"; in-reply-to should be pretty easy to add.

Also, it would certainly be nice to *sort* based on threading, too.  A
critical challenge with this is that the index file currently doesn't
have room for threading info, so you also have to update the index file
format to do it.  :(  Maybe someone can come up with a more extensible
format for it, which still loads reasonably quickly.  (Actually, scratch
the "still" -- it's pretty slow right now!)



> and uses 'X-Mailer' instead of 'user-agent' (read
> somewhere that X-Mailer is deprecated or something). But that is very
> easy to fix of course.
> 

Good idea.


-Lex