Zinc uses a setting called Clear to determine how long messages sent through the application should be retained. The Clear setting is accessed via the Settings tab within the admin console. This setting is intended to allow for increased organizational security through the ability to systematically delete messages after set periods of time. This applies to every message sent or received by someone in your organization. NOTE: Official Groups have their own Clear setting, which overrides an organization's global setting.
To specify a Clear setting, open the dropdown and select from the list of choices. Hit 'Save' after specifying your choice. New Zinc organizations are set to 90 days by default.