Hi

I am trying to export an org file to latex using the org-mode version
9.1.2. The input file structure is:
#+LaTeX_CLASS: LTR
* letter{}
.
.<some text here>
.
\closing{Thank you,}

Unfortunately, the compilation fails to generate the proper tex file
The body of the tex file is missing. The output tex file is:
\documentclass{letter}
...
\begin{document}

\begin{letter}
letter\{\}
\end{document}

It seems that the exporter does not recognize the letter environment.

I use auctex-11.89.5 and the .emacs file includes the following lines

(require 'ox-latex)
(with-eval-after-load 'ox-latex
(add-to-list 'org-latex-classes '("LTR" "\\documentclass{letter}"
("\\begin{letter}" "\\end{letter}" "\\begin{letter}" "\\end{letter}"))))

I've been using an older version of org-mode 7.x for many years and never
had this problem. But i understand that the export code has changed.
I appreciate your help
M.Zaki