Does it send a confirmation email?

I would need one in order to confirm that the user still uses the same email, rather than simply resetting the password

https://www.ads-software.com/extend/plugins/auto-expire-passwords/

Just curious if this will work if you login to the site via BuddyPress as well.

https://www.ads-software.com/extend/plugins/auto-expire-passwords/

Adding a function to require the reset of all passwords would be great. This is the code that I used on a multisite install:

$sort= "user_registered";

//Build the custom database query to fetch all user IDs
$all_users_id = $wpdb->get_col( $wpdb->prepare("SELECT $wpdb->users.ID FROM $wpdb->users ORDER BY %s ASC", $sort ));

//we got all the IDs, now loop through them to get individual IDs
foreach ( $all_users_id as $i_users_id ) :
$timestamp = 1331300040;
update_user_meta( $i_users_id, 'tmg_aep', $timestamp );
endforeach;

https://www.ads-software.com/extend/plugins/auto-expire-passwords/