What used to be called a Preservation Policy is now called a Retention Policy. That said, you might still see a folder in your OneDrive’s storage metrics* that’s called Preservation Hold Library, although the folder isn’t visible unless you’ve actually edited or deleted items that are affected under such a policy.
Your ‘permanently deleted’ mailbox items are held in the Recoverable Items folder, which is accessible from the Outlook Web App (OWA). Right-click on the Deleted Items folder and choose “Recover deleted items…” These are items that you’ve removed from the Deleted Items folder and will remain in the Recoverable Items folder for 14 days unless otherwise configured to 30 days by your system administrator OR unless there’s a Retention Policy in place that prevents anything from getting really, actually, truly, permanently deleted.
A caveat here: Retention policies applied to mailboxes require Office 365 Enterprise E3 or E5. This is because Exchange Online Plan 2 must be in place for mailbox retention. So if you have Office 365 Business Premium with its lesser Exchange Online Plan 1, then you can set a Retention Policy that covers your documents stored in SharePoint or OneDrive, but not on mail, calendar or contact items. Actually, you might be able to create such a policy that would seem to cover your Exchange items, but this data governance would not take effect until a qualified license would be put in place.
About Teams from Microsoft:
* To see your OneDrive metrics, go to portal.office.com, login, and then launch the OneDrive web app. In the upper right, click on the gear icon and choose Site Settings. On the Site Settings page under Site Collection Administration, choose Storage Metrics.