[imp] : change charset

[Carsten]

Hi team,

If I sent mails to my hylafax server (using wegfrontend or thunderbird) 
I have issues with the encoding / charset.

Special characters are always UTF-8 encoded, but are not properly 
decoded on the fax interface.

I figured out, that changing the encoding in thunderbird to 
"Mitteleuropäisch (Windows)" which should become "charset=SO 8859-1" 
solves the issue from thunderbird as sending client.
But for some reason I have to do this every time, I create a new mail item.

Now I try to figure out, how to set this the web front end of Horde/IMP 
as a "default" value.

I found some older posts about "nls.php" a.s.o. but they all say, that 
there was no final solution.

I would expect to have some file like
"./horde/imp/config/backends.d/mycharset.php"
at the end, but I need some advice on this.

Can You help?

br
Carsten