I want to add a folded, multi-line header (RFC2822, Sec.2.2.3) like
this:

X-Comment: foo foo foo
bar bar bar

using the headers_add option. I've experimented with it a little and I
think this works:

headers_add = X-Comment: foo foo foo\n bar bar bar

and even this:

headers_add = X-Comment: foo foo foo\n bar \
bar bar bar\n foobar \
foobar

for improved readability of very long comments. But before I leave it
in my config file, I'd like to know if anyone else has tried these,
successfully or not.

Thanks,
Adam