Using Eclipse Indigo and egit, everytime I commit a pop up appears and has my name and email in the author and committer boxes. They look fine. however, egit tells me:
Are you committing to git directly or to a gerrit review system? At least gerrit has case sensitive mail addresses, so they have to be entered exactly as known by the server.
In our company environment that has led to some confusion as they are stored as Jon.Doe@example.com in the LDAP server, but most people tried jon.doe@example.com with egit and got exactly your error messages.
Another trivial alternative would be some kind of bogus whitespace at the beginning or end of your author name in the configuration. You might not see it in the error messages. I have seen this kind of error happening when people copied content from a webpage into a rich text editor which stored more than the "pure" text.