Using New Outlook on Windows for personal email, calendar, and contact management
Since All is already selected, Focused Inbox is off, and the Inbox is sorted by date, this sounds more like a synchronization or view issue than a normal filter setting. In new Outlook, selecting All should display both read and unread messages in the current folder.
Please check whether the missing messages are visible in https://outlook.cloud.microsoft/mail/
- If the read messages appear on the web, the mailbox data is still intact and the issue is limited to the new Outlook app. Close Outlook completely, then open Windows Settings > Apps > Installed apps > Outlook (new) > Advanced options and select Repair. If Repair does not help, select Reset, then add the account again. Be aware that Reset removes the app’s locally stored settings and account configuration.
- If the messages are also missing on the web, check Archive, Deleted Items, and Settings > Mail > Rules in case a rule moved them. Outlook rules can automatically move incoming messages to another folder or delete them.
Also check Settings > General > Offline > Days of email to save and select a longer period if available, then save the change. Microsoft documents this setting as controlling how much past email new Outlook keeps available offline.
If the issue continues, could you confirm whether this is an Outlook.com/Microsoft 365 account or a third-party IMAP account such as Gmail, Yahoo, or another provider? That will help narrow down whether the problem is with new Outlook’s local view or the account synchronization.