I’ve created a new filetype, “usenet,” for Usenet messages. I would like files with this filetype to be highlighted exactly as if they had the “mail” filetype. Is it possible to tell Vim that I want to reuse the existing “mail” syntax definitions for this other filetype?

### What I’ve tried

* I tried writing `setlocal syntax=mail` in the `ftplugin/usenet.vim` file but this seemed to be ignored—running `:set syntax?` in a file with the “usenet” filetype just produced `usenet`.
* I also tried copying the `mail.vim` syntax file from `$VIMRUNTIME/syntax` into `~/.vim/syntax`, renaming it to `usenet.vim`, and changing the line

```
let b:current_syntax = "mail"

```

to

```
let b:current_syntax = "usenet"

```

This worked, but if a future version of Vim improves the `mail.vim` file then I would have to go through this process again (and it’s unlikely that I would even notice such a change in the first place). What I want, semantically, is to highlight “usenet” files as if they were “mail” files, which seems like it should be possible.