Merg Tag Notification

I'm using a custom function in my theme to generate a incremental number in the post meta table for each post (custom post type) that gets created ( kind of like the post id ) but it's a custom field.
I'm looking for a way to pull that field into the notification email the same way the post id can be done.
Keep in mind, the field is hidden, it's not viable in the admin editor while adding/editing a post and is not populated until the post is published ( like the post id).
Any help would be greatly appreciated.
Thanks.

This is my custom function:

function create_ticketid($post_ID) {
   global $wpdb;
   $latestid=$wpdb->get_var("SELECT meta_value from $wpdb->postmeta where meta_key='ticket_id' order by meta_value DESC limit 1;");
   if(!wp_is_post_revision($post_ID)) {
add_post_meta( $post_ID, 'ticket_id', $latestid+1, true );
  }
}
add_action( 'publish_my_postttype', 'create_ticketid');

I've tried looking at gform_after_submission and gform_pre_submission_filter but can't seem to get anything to work.
Please help.
Thanks.

It's been over a month and not one response?