On multiple computers, in both firefox & IE updated version 9, when i send a bulk email to the same recipients I have been for years, i get the following message and cannot send the email at all!! 

the email address' are correct, i cleared cache, i tried on multiple computers, i tried on firefox & Internet Explorer - problem still exists!

Please help as this is a big problem!

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.