So I just tested that, sent myself an email to my
username@icloud.com and it bounced back as not a valid email address. I have the same problem with
myusername@mac.com that is no longer working.
Not sure why yours is not working.Ijust logged into icloud.com, launched MAIL and sent my self a test email @icloud.com.It was delivered
Have you converted?"officially" to the cloud?
I can;t recall what the process is but I think you have to do something to migrate your Mobile Me stuff, including accounts, to iCloud.
Another neat thing I discovered. Mail in the cloud keeps track of all my email addresses including the gosh darn complicated ones whic Evernote and similar services provide (which I can never remember to email something to those storage or archival sites). That is a really welcome feature!