Hi all,
Yahoo have made it a bit more difficult for third party apps to access their service. You can allow Aqua Mail access to Yahoo by generating an app specific password:
1. Sign in and go to your Account security page.
https://login.yahoo.com/?done=https%3A%2F%2Flogin.yahoo.com%2Faccount%2Fsecurity%3F.scrumb%3D0&src=noSrc2. Click Generate app password or Manage app passwords.
3. From the drop down > choose "Other app" > enter a custom name > tap / click Generate.
4. Follow the instructions below the password.
5. Click Done.
6. Use this app password and your email address to sign in Aqua Mail.