Spam Filter programs

Hello. I am currently looking for some advice on some Spam Filter software and/or appliances for the company I work for. We are currently using Symantec’s Mail Security v. 5.04, however I have not found this to be very user friendly, and it certainly seems like we spend a lot of time administrating it. Overall, the end users, specifically the owner, are not happy with this solution.

I know that Spam as a whole is a huge issue worldwide, and that some spam showing up in email boxes should be expected, however there has to be something that works better than this program.

Any thoughts or suggestions would be greatly appreciated.

Thanks for your time.