Hi @LeffDesign
No, this is not correct.
The ‘acf/pre_save_post’ is a filter, not an action. You will need to connect this to a custom function which accepts and returns the $post_id parameter. Before returning the $post_id, you can then fire the sendMail() function.
Please read the doc article on creating a post via the acf_form to understand how this filter works:
http://www.advancedcustomfields.com/resources/tutorials/using-acf_form-to-create-a-new-post/
Thanks
E
