Jani Nikula <jani@nikula.org> writes:
> My quick guess is that gmime stops header processing at that point, and
> all the headers we require are after that invalid header. 

I can confirm that.  I adapted one of the example programs which comes
with gmime to read out the "From" header, and it indeed was not found,
because it came after the BOM.  Therefore the root of the problem is
indeed with gmime not notmuch.  I will send an email to the gmime-devel
list, to ask them if they consider this to be a bug. 

> If it were a real email and not spam, I'd be interested... this could be
> intentional to trick a spam filter.

quite possible.  Still a bit annoying ...

Andreas