What are email server settings for my iCloud email account?
For information on iCloud mail server settings, please see
http://support.apple.com/kb/HT4864?viewlocale=en_US

Do you have iCloud Two Factor authentication turned on by any chance? If you do, you will need to generate an App-Specific password in order to connect to the iCloud SMTP server. See steps below:
1. Log into iCloud.com
2. Scroll to "Security" section
3. If "Two-Factor Authentication" is turned on, please click on the "Generate Password" link located next to App-Specific Password
4. Enter the password generated into the password field in the app