If you accidentally mark a message as spam, you can restore it from the spam folder. To do this, tap the menu at the bottom-left corner (it should say Inbox if you’re in the inbox), tap Spam, and then open the message. Tap More at the bottom-right corner and select Not spam.
If you marked a message as spam by accident, you can restore it. Just click the Spam folder in the left panel, select the message, and click Not Spam at the top.
