Why don't you share the reviewers' email addresses in the directory?
In our public book reviewer directory, many reviewers don't want to expose their email address. They prefer to be contacted via the contact form on their website. We try to link you directly to this contact form if possible. Otherwise, we link you to the page where their contact email address is displayed. Secondly, exposing their email address in a easily consumable form would catch the attention of spammers and we want to safeguard against this.