phswartz,
I will make a general statement about spam and virus filtering on Scalix. Technically speaking, any spam or virus filtering software CAN be utilized with Scalix so long as it supports sendmail as a client OR acts as a mail filtering gateway.
I have attempted installs of many different spam and virus filtering options including but not limited to:
SpamAssassin
clamav
amavisd-new
Mailfilter
MailWasher
Spam/Virus filtering appliances (IE Barracuda Networks)
I've had success with all of them and they all have their pro's and con's. Of course, what packages you need depends on what you want to install.
I recommend using MailWasher and Clamav. The installation is relatively painless and the vast majority of users who have tried it have a completely functioning setup in less than one hour. There is documentation that should walk you through the majority of the issues of setting it up and configuring it in these forums, FireTrust's MailWasher forums as well as the Scalix Wiki.
I can safely say that for ease of use (very important in a corporate environment) MailWasher is definately much easier to use and provides a nice web interface for end-users to utilize to manage their own quarantined messages. From an administrative stand point on a large installation, this is paramount as it relieves a mail administrator from the dreaded, "The spam filter blocked an important e-mail. Can you fetch it for me?" type of questions. I can now tell them to log into their message quarantine, locate the message and click the "not junk" button by the message to get it.
Additionally the installation method for MailWasher and clamav is a short process with fewer points of failure.
Anyhow, please check it out, it may help you out ;-)
Hope that helps!