In Drupal 8 the Drush command drush variable-set no longer works.

From reading (here) it appears that Drupal 8 has a new "configuration" system that replaces the old (Drupal <=7) "variables". But what is the new Drush command to achieve the same ends?

Specifically I want to convert the commands:

drush variable-set site_mail [email protected]
drush variable-set update_notify_emails [email protected]

to the new Drupal8/Drush8 equivalent...