get venue id from event post

I’m doing some custom coding to send an email to the event organizer with event details. I’ve pretty much got it working but I’m having trouble getting the venue ID from the Event post.

I’ve tried:
$venue_id = $_POST[‘venue’][‘VenueID’];
$venue_id = $_POST[‘VenueID’];
$venue_id = $_POST[‘venue’];
$venue_id = tribe_get_venue_id( $post_id );

Can anyone point me in the right direction here. It can’t be this hard!!!