Hi,
sorry I misread the post.
Example of how to add a message to a template.
1. go to admin -> International -> Translations
2. Modify translations
Type of translation -> Email translations
Select the type of email content -> Body
Select your theme -> your theme
Select your language -> your language
3. find Core emails -> contact_form
4. edit -> add {message}
5. Repeat the process for all languages
6. go to ./modules/contactform/contactform.php
7. comment this line
$var_list['{message}'] = self::MESSAGE_PLACEHOLDER_FOR_OLDER_VERSION;
to
// $var_list['{message}'] = self::MESSAGE_PLACEHOLDER_FOR_OLDER_VERSION;
8. save
9. clear cache