Every time I try to send a group email in bcc I receive the following message:

Please use the following format for email addresses: *** Email address is removed for privacy ***. If you're using category names or nicknames, make sure you don't have any typos. Unknown names:

It suggests an email address that is incorrect (even though it isn't) I delete the email address and hit send...it then comes up with the same error message and a different email address and so on and so on. This is driving me crazy I have spent 3 hours trying to sort this out please, please help!