When trying to send mail through "Contact Us" footer it gives this error. I am using XenForo. I am also using Mandrill, the mails sends successfully but for some reason this error appears. I heard it's because of php-fpm issue.. While I know you only support regarding centmin it self, i thik this issue is not to do with my forum software.. and if it was, you also run xenforo so you might know why?