The Spam and Not Spam buttons help to “teach” the Yahoo! server what messages it should classify as spam based on the content and/or headers. When you use either button, it is instructing the spam filter that it did the wrong thing. Clicking “Not Spam” means, “the content of this message is not spam,” not “I always want to receive messages from this email address.
What you should do is “whitelist” the particular sender, by creating a filter which specifies email from that address will always go to your Inbox.
The Spam and Not Spam buttons help to “teach” the Yahoo! server what messages it should classify as spam based on the content and/or headers. When you use either button, it is instructing the spam filter that it did the wrong thing. Clicking “Not Spam” means, “the content of this message is not spam,” not “I always want to receive messages from this email address.
What you should do is “whitelist” the particular sender, by creating a filter which specifies email from that address will always go to your Inbox.