This is an important update for any Circle clients using the Mollom module on their Drupal site: the module is now unsupported due to a security issue the maintainer didn't fix. Circle is therefore in the process of uninstalling the module from all sites and servers today (7th June 2018).
You can replace Mollom's functionality with a combination of the reCAPTCHA and Honeypot modules. If you're a Circle client and you'd like to do just that, please let us know in the usual way by submitting a support ticket via our intranet.
As ever, please don't hesitate to contact us if you have any questions.