With IPHost Network Monitor you can run simple snmp requests against a Fortinet device in your network.
fgAppIMMessages
fg App IM Messages
1.3.6.1.4.1.12356.101.10.110.1.1.1
Total number of IM messages processed in this virtual domain
Back to FORTINET-FORTIGATE-MIB MIB page.
IPHost Network monitor allows you to monitor fgAppIMMessages on Fortinet device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Fortinet switches right now.