York Zhao <gtdplatform@gmail.com> writes:

>> #+options: title:nil
>
> Thanks a lot! This worked, but still problematic. If I have "#+options:
> title:centered" for letter 1 but "#+options: title:nil" for letter 2,
> letter 2's
> setting will override letter 1's. I.e., letter 1 will have no title now.

Use the :EXPORT_OPTIONS: subheading options.

> Also, I was looking into ox-koma-letter.el trying to find some clue, but I
> couldn't find where it handles the "title" option.

Probably in ox.el or ox-latex.el depending on what you have got in mind.

> The closest I've got was `org-koma-letter-subject-format', which can be
> set with "#+OPTIONS subject". But it seems that the "subject" option
> works the same as the "title" option, and has exactly the same problem.

I don't understand this part.  The documentation of ox-koma-letter.el is
at the top of the file.  There’s also a tutorial on Worg.

Rasmus

--
Enough with the bla bla!