Email spam detection relies on multiple factors such as the sender's reputation, message content, attached data and files, and how many recipients are included.

Because of this filtering, legitimate emails can sometimes be mistakenly classified as spam and sent to the Junk Email folder.

To unmark an email item as Junk Email in Outlook, right-click on the email message, click Report, and then click Not Junk.

You will see a pop-up window notifying you that the email address will be added to Safe Senders and that future messages from the sender will never be sent to the Junk Email folder. Click Report to report the message as Not Junk. The email will then be moved from the Junk Email folder to your Inbox.