We are running ZCS 8.06 currently and it's been running fine for a good 6 months. In the last month we've been inundated with Spam. Some users more than others, but some of our users are seeing 100+ emails/day which are entirely rubbish.
I was wondering how the rest of you address this problem. Are you doing any tuning on Zimbra itself or are you using any hosted services which filter the mail before it reaches the Zimbra MTA?
Our infrastructure is all virtualized/cloud so I'm not looking to deploy a hardware solution such as Barracuda, but would be interested in a service that acts as an MX for our domain(s) and filters out all the garbage before it hits our server.
If there's something more we can do on the server side, let me know.
I don't have DNSBL/SBLs in use yet, but was considering using Spamhaus or another solution to block the connections to the server.