Actually, I’ve just installed the plugin fresh and I’m getting that isValid error showing in the logs again now. In the browser console, I see an internal server error on admin-ajax.php and VM:2330:1 if that helps?
Prior to the upgrade, I did see an error – [17-Jan-2018 09:38:04 UTC] PHP Fatal error: Call to undefined method Mail_Bank_Zend_Validate_Ip::isValid() in …. /wp-content/plugins/wp-mail-bank/lib/zend/validate/class-mail-bank-zend-validate-hostname.php on line 1705
But this cleared after I refreshed the page and there are no errors after the upgrade.
That’s great. I didn’t expect such a quick reply.. thanks 🙂