How to Recover a Spam Message in Facebook Messenger
To access Filtered Requests from Facebook’s main pages:
Select Messages icon at the top right of your main Facebook page, or Messenger in the navigation panel at the left side. Select the Gear icon to the left of Messenger, at the top of the list of people who have sent you messages. Select Message Requests in the drop-down menu. Choose See Filtered Requests to see all the messages that Facebook has moved to this folder. Find the spam message you’re looking for and accept the message request. This will move the conversation into the regular section of Messenger, where you can contact the user as you would any other. You also can copy the information if you don’t want to reply immediately.
How to Recover a Spam Message in the Mobile Messenger App
You can find message requests using the Facebook Messenger mobile app, too.
Select the People tab at the bottom of the Messenger app. Select Contacts at the top right (look for person icon with a plus sign next to it. ) Select Requests. Any requests and spam directed to this folder appear at the top of the resulting screen. To learn more about the sender, open the request; the sender will not know you viewed the message unless you accept the request. You can accept the request or click it for more information. You also can copy or delete it.