Yahoo Mail places any emails that it interprets as SPAM in “Spam” folder located in the left navigation after you logged in. You’ll have to check this folder any time for regularly to make sure an email you wanted to receive did not end up here. To whitelist our email firstname.lastname@example.org with Yahoo, you need to set up a “filter”.
Steps to Whitelist Email Sender or a Domain in Yahoo! Mail:
1. The first user has to Log-in Yahoo Mail account.
2. If you found an email from email@example.com in your Yahoo! Mail spam folder, open it and click “Not Spam” button.
3. Click “Options” in the top left corner, then click “Mail Options”.
4. Select “Filters” in the mail options area.
5. On the Filters page, click “Add” button.
6. Define filter name, and select “Contains” from “Sender” pull-down menu, then enter firstname.lastname@example.org into the dialog box, which tells the system to put email with email@example.com in your inbox and not the spam folder.
7. Select “Inbox” from “Then deliver the email to the following folder” pull-down menu, and then click “Save” button above.