Hello,
I'm new on this(at least any) forum and my solution i've found myself
The problem was:
I tried to import a user .cvs file with chinese characters.
I prepared my import file with a text editor(ultra edit).
The import format was correct - but always said that the email is uncorrect - but in the file they were 100% correct.
The message didn't give an example of the wrong data.
So i deactivated the mail function (regex test) to see the wrong email addresses within the token table.
==> and there i could see that i had a character encoding problem...
Saving the file with utf8 and import with utf8 worked.
Sounds logical but i was nearly to give it up and cost me time...

=> suggestion for a new release: show the corrupt data..?!