Reinstate email changes

test/mailers/previews/identity_mailer_preview.rb

@@ -0,0 +1,13 @@
+class IdentityMailerPreview < ActionMailer::Preview
+  def email_change_confirmation
+    new_email_address = "new.email@example.com"
+    user = User.all.sample
+    token = user.send(:generate_email_address_change_token, to: new_email_address)
+
+    IdentityMailer.email_change_confirmation(
+      email_address: new_email_address,
+      token: token,
+      user: user
+    )
+  end
+end