jciconsult wrote: The error is being generated by field validation not after the submit is done. You are using your own field validation. I have posted the issue on the forum but have received no response.
forum.joomla.org/viewtopic.php?f=615&t=750294
Looks like this is (unfortunately) a pure Joomla issue.
Tests done:
1. Joomla user manager does not allow it!
2. CB extra email field allows it (so CB is validation correctly)
3. CB User creation with primary email field is being rejected from joomla (CB passes its tests but what is sent to joomla is rejected)