How do I remove an e-mail address from being sent to the SPAM and deleted after a month?

(I received two answers to both prior questions but neither works) First I was advised to go to the Spam folder and click on the address and move the message to the In Box. Doesn't work as Yahoo removes all Spam after a month so there is no message in Spam. Second answer after I resubmitted the question and explained this was: Click Not SPAM by the message. Again, there is no message as it has been deleted by Yahoo so is not available. The question remain, how can I reinstate an e-mail address so it is no longer considered SPAM?