Message Not Delivered: Email address format not supported
The message could not be delivered because special characters (non ASCII) in the email address are not permitted by one of either the sender's email program or the recipient's email program.
Check and the email address(es) of the recipient(s) for unusual characters. If an error is found, correct it in contacts list or address book for next time.
Otherwise, contact the email provider for help.
5.6.7: Official Definition
A permanent failure is one which is not likely to be resolved by resending the message in the current form. Some change to the message or the destination must be made for successful delivery.
This indicates the reception of a MAIL or RCPT command that non-ASCII addresses are not permitted