Hi everyone.  I really need some help.  I send out an email newsletter via hotmail/outlook.  My contacts are organised in groups.  When I've tried sending out to certain groups lately I've received this 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: ridof."   Please can anyone shed light?!

(Original title: Corrupted contacts? Help please!)