ServerPilot enables Postfix so your apps can send mail from your server; however, ensuring 100% email delivery yourself can be tricky.
So email coming from your server is not marked as spam, you can sign up for SendGrid and integrate its mail delivery service with Postfix.
First, SSH in to your server as root and run the following command:
sudo apt-get install libsasl2-modules
Now, open your Postfix config file, located at /etc/postfix/main.cf and add the following lines:
smtp_sasl_auth_enable = yes smtp_sasl_password_maps = static:yourSendGridUsername:yourSendGridPassword smtp_sasl_security_options = noanonymous smtp_tls_security_level = encrypt header_size_limit = 4096000 relayhost = [smtp.sendgrid.net]:587
Save the file and restart Postfix with this command:
sudo service postfix restart