Sending, receiving, and organizing email in Outlook.com
If this is a personal Microsoft email account, such as Outlook.com, Hotmail.com, Live.com, or MSN.com, unfortunately there is an important limitation.
Microsoft states that Junk Email is retained for 30 days and then automatically deleted. Once Outlook automatically deletes it from the Junk Email folder, it is not recoverable. See official document here: https://support.microsoft.com/en-US/Outlook/filter-junk-email-and-spam-in-outlook