Under 10.10.2, Mail is currently version 8.2. My Mail iCloud account is setup as IMAP; and the SMTP settings in my iCloud account's SMTP set-up are as shown at this Apple Support link iCloud's Mail Settings
While I don't have any problems sending & receiving email out of my iCloud account, Mail's Connection Doctor reports that while my iCloud IMAP connection and login succeeded, it reports iCloud SMTP "Trying to log in to this SMTP account failed. Verify the username and password are correct."
I've tested sending emails from my iCloud account to a Yahoo Mail account, accessed from the web (the Yahoo account is not set-up in Mail), and the test email is received without problem at my Yahoo Mail. ...This would seemingly indicate the SMTP settings in my iCloud setup are working.
I've re-verified the iCloud account SMTP settings (SMTP server address, login name - full email address, password), but Connection Doctor continues reporting the same SMTP login error.
Any thoughts as to why Connection Doctor reports the error regarding iCloud SMTP?