fortimail operating system

It' s built on top of linux for sure and uses " resiserfs" for the jourmal fs. On the database, and after speaking with the product manager he ensured me that both the spam dectector database engined are inhouse crafted. So we can rule out MySQL, PostgreSQl and Oracle. I guess they built fortimail similar to Mysql and spamassasin if I had to guess.

what is meant by inhouse crafted ?

Just that, fortinet engineers designed the engine and detectors in-house and it' s not hacked from the opensource community " . You can speak about this with the product-manager ( Brian Schwarzkopf ) , but I highly doubt that he will not go into details as to what they built specifically.

Dear emnoc , Thank you very much