Currently Being ModeratedMar 6, 2013 6:51 PM (in response to Tomdbl)
You could try this:
1. Delete the iCloud Mail account, use the '-' button and add it back manually.
2. Click the '+' button to create a new account.
3. Hold the option (alt) key down to change the 'Create' button to 'Continue' (this is to prevent your Mac from setting up the account for iCloud automatically).
4. Click 'Continue'.
5. Set 'Account Type to IMAP, enter a description (e.g. 'iCloud')
6. User Name: email@example.com (use your @me.com address from your iCloud account)
7. Set the Incoming Mail Server to imap.mail.me.com Click 'Create' (don't hold the option key down this time).
8. Enter the SMTP server address - smtp.mail.me.com - and click 'Use Authentication'.
9. Click 'Create'.
10. Check the Advanced settings in Mail Preferences>Accounts, select the account and click the 'Advanced' tab: set the port number to 993 if it isn't than already and make sure that 'Use SSL' is checked.
All iCloud Mail server settings can be found here: http://support.apple.com/kb/HT4864