"User already exist in your org"

"User already exist in your org"

Hello,

I've just read a discussion about this issue, which didn't solve my problem.

I'm trying to add the following emails:

sales@kiss-my-boutique.co.uk
returns@kiss-my-boutique.co.uk
orders@kiss-my-boutique.co.uk

I'm getting an error message each time I try and add them. None of them are primary or secondary emails and none of them have been created as users before. I know this as when I try and login and do 'forgot my password' all I get is an error message saying 'user invalid'.

Please advise.

Thanks.