By default, Spanning Backup for Office 365 retains your data as long as users have Spanning Licenses. You can set up a mail retention policy which will delete any email messages in your backups with a received date older than the retention period set. 

The email retention period will apply to all Spanning licensed users in your organization.

For example:

• An organization sets a 180 day email retention period in Spanning
• Spanning will delete all email existing in any backup with a received date greater than 180 days, and continue to do this on a daily basis automatically
• For new users being backed up after a retention policy is set, no emails older than the retention period will be backed up
• The mail retention policy setting for your tenant is displayed on the Settings page. 

If you would like more information about mail retention, or would like to set up a policy for your organization, please contact support@spanning.com. The request to enable a mail retention policy must come from a Global Admin in the tenant. 

Any changes to the retention policy will be tracked in the immutable Activity Log with a record of the admin who requested the policy change. 

To learn more about Retention for other workloads, like OneDrive, SharePoint, and Teams. See the article Tenant Wide Retention.