F-SECURE ANTI-VIRUS FOR MICROSOFT EXCHANGE 7.10 Administrator's Manual page 29

Figure 2-3 Deployment in an environment with Edge, Hub, Mailbox and Client
Access Server roles deployed on multiple servers
If the Exchange server roles have been deployed on multiple servers, you
should deploy F-Secure Anti-Virus for Microsoft Exchange as follows:
Installing F-Secure Anti-Virus for Microsoft Exchange
Install F-Secure Anti-Virus for Microsoft Exchange on all the servers
where Exchange Edge, Hub and Mailbox Server roles are deployed.
If the Exchange role is changed later, the product has to be
reinstalled.
Note that you cannot install the product on a server that has only Client
Access and/or Unifield Messaging Server roles deployed.
CHAPTER 2 29
Deployment