I will suggest that the "much better spamfilter" be disabled by default because:
1) it's 3 daemons with their subprocesses use 200+MB of committed memory right out of the box.
2) The amavisd requires fixing just to start it.
3) The content filter is plain stupid! We are a software development company and we had a whole day lost on a project until finding out that it blocks our own email and clients didn't receive their updates that contained zipped exe files (remember software company). Some "much better" programmer has been coding unchecked there.
4) Having an antivirus service on a web server IS BAD DECISION! You can be flooded your performance WILL be hampered when a large attachment is present. Generally content filters are supposed to go on separate servers.
The content filter should be disabled by default and whoever want's it could enable it. It doesn't run out of the box anyway.