The email seems to be delivered but it is non received by the destination

[Storyteller]

This is the log:

STARTTLS=server, relay=[192.168.X.YYY], version=TLSv1.2, verify=CAFAIL, cipher=ECDHE-RSA-AES128-SHA256, bits=128/128 STARTTLS=server, cert-subject=/CN=EXC02, cert-issuer=/CN=EXC02, verifymsg=unable to get local issuer certificate from=<prossi@sourcecompany.com>, size=5022, class="0", nrcpts=1, msgid=<985f73a55b014992adb56d7b87e1fcfe@destcompany.coop>, proto=ESMTP, daemon=SMTP_MTA, relay=[192.168.2.219] to=<b.gates@destcompany.coop>, delay=00:00:01, xdelay=00:00:01, mailer=esmtp, pri=35853, relay=mail.destcompany.coop. [83.xxx.yyy.8], dsn=2.0.0, stat=Sent (OK 9E/DA-03372-A4C53AB5)

I've removed sensible data. The last part of the log (Sent (OK 9E/DA-03372-A4C53AB5)) means a successful deliver to destination, doesn't it? The email is not received and I have no return message.

Fortimail is used by a gateway in front of two Exchange.

Any suggestion?