For one client we remotely administrate their spam filter. I'm glad the setup was done by prior IT as the interface was a little different that what we are generally use to with other software. I have to say I am pleased with the functionality after getting use to it and support is quite helpful. I also know of friends personally who use the software and are content with it over some of the other "free" AV out there.
we have used kaspersky mail security for a brief time. we were planning to migrate from mcafee and decided to test it. installation and everything was very smooth but it let more spam than any other products. i contacted support and they said there is nothing they cant do about it. Aside from the fact that it has no database access, and cannot retroactively remove SPAM.
i was 18 months ago so not sure if they have same issue.
Kaspersky has been around for nearly 20 years. I've been a happy customer using their total internet protection product. Recently our manager decided to switch over. When it comes to spam filtering we feel it's doing its job well. We get reports and can evaluate what's going on. System resources generally run low so users aren't noticing any hold up. Would recommended!