What mail .deb package is used with TrueNAS

[Daisuke]

I don't see Postfix installed, what is the mail system used in TrueNAS Scale?

Code:

root@uranus[~]# find / -type d -name postfix
root@uranus[~]#

I want to look how the mail related settings defined in web interface are saved inside the server configuration files. If you could point me where there are these files, it will be appreciated.