You will have to write a plugin which creates a daily cron job in the WordPress system.
Here’s an article describing how to write a cron plugin:
The function (callback) that you trigger in the cron plugin will use WP_QUERY to get a list of all your published custom post types after a certain date.
e.g.
$my_query = new WP_Query( array(
'post_type' => 'your-cpt-name-here',
'order' => 'ASC',
'posts_per_page' => 1,
'date_query' => array(
array(
'after' => '1 day',
)
),
) );
Run through the results and send an email using wp_mail()
.
Alternatively, ask on fiver.com and get a developer to do it for you. It’s pretty simple so won’t cost very much at all.