[Since version 4.1.6](https://wordpress.org/support/topic/how-to-disable-mshots-service/#post-12939728), Akismet has a filter which [allows you to turn off the site preview popups](https://wordpress.org/support/topic/how-to-disable-mshots-service/#post-12944077) (”mShots”):

function disable_akismet_mshots( $value ) {
return false;
}
add_filter( ’akismet_enable_mshots’, ’disable_akismet_mshots’ );