I am also thinking same way that my server is clean bcoz i have tried most of the antivirus scan online. i saw the log file of Norton but there is nothing new, viruses found in spool directory and it has been deleted by the Norton. But it’s nothing new or suspicious.

Yes Norton scan the mail header and attached file (encrypted also) and can detect, delete those virus under the encryption

Now the thing is Norton and barracuda (and most of the online scan) can not detect some virus than how come CBL software can detect them….what are the software they are using to detect the virus (it must be more effective than any antivirus available in the market). I tried to know the virus name but CBL person said that we don’t keep history of each server as we have thousands of entry so its hard to give u particular virus name for particular server.

As u said I can do only one thing, I can send a group mail to my all client to update their network (all pc). And use good antivirus. (I guess this is the last solution)