Hey Nicholas!

 NB> I believe this client forces utf-8 when posting, which is fine.

From the PID I am gathering the client is nttp based.  I've run across similar strategies here and there.  The output looks fine from this angle.

 NB> I do have other clients for testing purposes that can send it back
 NB> in CP866, but why?

Because we can?  Besides CP866 is one of the few encodings that they - whoever 'they' are - get right.

 NB> Be prepared to be in the fight for the long haul. :)

I've been doing so off and on and probably will continue as long as I have a haul nevermind a long one.

Besides it isn't the size of the haul but the quality.  ;-)

Life is good,
Maurice

-o   -o    o-   o-  -o   -o    o-  -o    o-  -o   -o   -o    o-  -o   -o   -o
 (\   (\  /)   /)    (\   (\  /)    (\  /)    (\   (\   (\  /)    (\   (\   (\
 ^^   ^^  ^^   ^^    ^^   ^^  ^^    ^^  ^^    ^^   ^^   ^^  ^^    ^^   ^^   ^^
... Monig biš uncuš treowgešofta, teoraš hwilum.
    Many a trusted friend will prove to be unknown, will fail at times.
--- GNU bash, version 5.2.26(1)-release (x86_64-pc-linux-gnu)