How to block spam newsletter subscription?
I have added captcha and form key for newsletter subscription but still get spam subscription.
These subscriptions have unsubscribed status.
1.Enable the newsletter email confirmation setting from Magento 1 admin as, System >> Configuration >> Customer >> Newsletter >> Need to confirm : Yes
2.And as Jake mentioned you need to install the google Invisible recaptcha plugin. you may check below from Amasty, https://amasty.com/magento-google-invisible-captcha.html