Cannot relay emails from Zimbra to Fortimail

I cannot configure my zimbra server to relay emails to Fortimail, all outgoing emails have an error:

mail for 192.168.1.20:25 loops back to myself

Hostname on Fortimail and domain name is the same as on my Zimbra server.

I use this Zimbra command to send emails to fortimail (192.168.1.20 - Fortimail)

zmprov ms zimbra.domain.local zimbraMtaRelayHost 192.168.1.20:25