I want to install some form of spam filter to my server. I host a number of domains on the server with pop3 accounts, but currently have no spam barrier.
I would like suggestions and costs for spam filter solutions. I have come across clients who use reverse DNS lookup and would be interested in proposals for that route, but I would also ne interested in other options.
The server configuration is Linux Ubuntu 8.10 hosted by [login to view URL] in the UK