After updating Quicken 2013 to R6, creating a new Cloud ID using an email address that contains a period in any part of the name (other than the domain separator) results in the message
"Invalid Email Address. Check your email address and try again."
Examples of email address formats that will cause this message are:
UPDATE (11/12/12): This issue has been resolved by R7. Please update your Quicken program to the latest release (R7, as of 11/27/12).