In your yahoo account settings under "Account Security", you will need to make sure that "Allow apps that use less secure sign in" is turned on as show in the image below:
Do you have Yahoo!'s 2-Step verification set up? Click here for details on Yahoo!'s 2-step verification
If yes, then you will need to use an "app-specific password" for Aid4Mail. Click here to learn more.
The IMAP settings screen should look like the image below.
Note: Insert your own username and password but leave the "Namespace" field blank.
Should you require any assistance, please don't hesitate to contact the help desk.
If you would like to buy an Aid4Mail license please visit the Aid4Mail website.