All emails in your mailbox, regardless of which folder you save them in, count towards your email quota limit (the maximum allowable mailbox size). This includes your Deleted Items folder; however, you can configure Outlook to automatically empty your Deleted Items folder every time you exit.
To enable the Empty Deleted Items folders when exiting Outlook feature, follow these steps:
- Click the File tab.
- In Backstage view, click Options on the left‑hand pane.
- On Outlook Options menu, click Advanced on the left‑hand pane, and in the Outlook start and exit group, select the Empty Deleted Items folders when exiting Outlook check box, and then click OK.