Nodeemailer not working

No, that was not what I wrote. The communication of your server uses port 25 to send emails to other servers. Most providers are blocking this port by default to prevent spam.

The log is in /var/log/exim4/mainlog, you can use tail or cat to get some output. But please be informed, that you already should know this when you’re using hestia → Please read this, before you start!