Apple requires all third-party apps that access iCloud information to utilize app-specific passwords, and this includes Edison Mail app.
Please follow the steps below to correct this issue:
- Enable 2-factor authentication for your iCloud account following the instructions here.
- Sign in to your Apple ID account page.
- In the Security section, click Generate Password below App-Specific Passwords.
- Follow the steps on your screen. Generate an app-specific password.
- After you've enabled 2-factor authentication and generated an app-specific password, type or paste it into the password area in Edison Mail in lieu of your regular password.