Path not Visible from where we received mailed inside the lan to lan-FORTIGATE 60E

[Insaf_nazar]

When we send a mail from 10.10.10.12 to 10.10.10.120. the source address we get as 10.10.10.1(  firewall gateway) when we check mail logs. no any Natting is added. can someone give me a solution....