Quoting David Bremner (2013-10-27 12:48:24)
> tomi.ollila@iki.fi writes:
> 
> > In thread starting from id:08cb1dcd-c5db-4e33-8b09-7730cb3d59a2@gmail.com
> > David wondered in id:87y58xv71x.fsf@zancas.localnet what filtering
> > is done by CLI and what by lib.
> >
> > But where should the "problem" presented in the Subject: header should
> > be handled. I did some hacks to emacs client to drop the ^J (newline)
> > characters from Subject: and From: headers but should these be filtered
> > in CLI (or in lib) instead?
> >
> 
> Eventually we decided this was a front-end isssue. The emacs front-end
> fixed this  with commit 0.16-111-ga7964c8


I agree that this should be an issue for the MUA.
FYI: alot also normalizes newlines and tabs in subject lines..
https://github.com/pazz/alot/blob/master/alot/db/utils.py#L369
I cannot reproduce the original issue with the escaped UTF8 header not being interpreted.
This works fine for me in alot.

Best,
/p