This workaround will let your Zimbra Collaboration platform run without antivirus. Go to Server Zimbra includes Clam AV 0.98.4 as of ZCS 8.0.7 .
The clamav-0.98.4 directory from an installed ZCS 8.0.7 or later installation can be copied directly to an earlier ZCS 8.0/7.2.x server.
Clam AV has two modes of operation; a program that loads into memory only when you want to scan a file, or for more regular use (such as scanning all incoming e-mail), a program that connects to a daemon that is always running.
Clam AV Does not come with a GUI by default so you must use the Terminal to use it.
Would you like to answer one of these unanswered questions instead?
Zanna's suggestion about installing from source is the correct solution to the problem.
As the message is just a warning, you can disregard it.