How to Host Email Using iRedMail
ServerPilot installs and configures Postfix so your scripts can send email from your server. However, ServerPilot does not manage mail servers for hosting your domain's email.
If you need to host your own email, you can use a separate server running iRedMail. iRedMail is a control panel dedicated to email hosting. DigitalOcean has a good tutorial for installing iRedMail on Ubuntu 12.04.
Use a separate server for iRedMail. Installing iRedMail on a server managed by ServerPilot will break your websites and iRedMail.