XF 1.5 New user with banned email address but no record


Active member
Chap wants to register on my site but can't because 'the email address you entered has been banned by the administrator' but I cannot find any record anywhere of his email address being deleted and nor is it in the banned users list so that I can unban it. IP checks out, email address ends in hotmail.com and all seems legit.

Scratching my head. Any ideas anyone?