I install Magento 2 on my server VPS: ubuntu 16.04, Nginx 1.10, MySQL 5.7, PHP 7. Site works, but can not sign on subscribe "Something went wrong with your subscription.". Transfer emails not works too. What have I done wrong? Maybe I need something to install on a server More?
Make sure Postfix is installed and configured as a NULL Client.
Install postfix by
apt-get install postfix and configure in accordance with this official postfix guide