• Before upgrading or downgrading the firmware, always perform a complete backup, including the configuration file and other related data such as the Bayesian database, dictionary, and block and safe lists. For details on how to perform a complete backup, see “Backup and restore”.

• Upgrade to the latest available firmware. After downloading the firmware file from Fortinet Technical Support (https://support.fortinet.com/), back up the configuration and other data, then go to Monitor > System Status > Status, and, in the Firmware Version row, select the Update link.

• Configure the FortiMail unit to accept both scheduled and push updates of antivirus and attack definitions. FortiGuard updates are configured in Maintenance > FortiGuard > Update.

• Before a FortiMail unit can receive FortiGuard Antivirus and/or FortiGuard Antispam updates, it needs to connect to the FortiGuard Distribution Network (FDN). FDN connection status can be checked in Maintenance > FortiGuard > Update.

• Allow the FortiMail unit access to a valid DNS server. DNS services are required for many FortiMail features, including scheduled updates and FortiGuard Antispam rating queries. The DNS server used by the FortiMail unit is configured in System > Network > DNS.