Sending, receiving, and organizing email in Outlook.com
Selecting Empty folder on the Inbox normally moves the messages to Deleted Items, rather than permanently erasing them immediately. Please avoid emptying the Deleted Items folder.
Once the current process finishes, open Deleted Items, select the messages that came from the Inbox, and choose Move > Inbox. If there are many messages, you can sort them by the deletion date and restore them in smaller groups.
If some messages do not appear there, select Recover items deleted from this folder at the top of Deleted Items, choose the missing messages, and select Restore. Items removed from Deleted Items are generally recoverable for up to 30 days in Outlook.com.
Please let me know whether this is a personal Outlook.com/Hotmail account or a Microsoft 365 work or school account if the recovery option is unavailable.
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