The best feature is that it's free for small business! I love how easy they make setting up filters as well; you can set rules by keyword or even just send out an alert if there are any known spam/malware emails in your database so nothing gets through without approval first (I'm not sure this option exists yet). It doesn't have all of our other features but we were able to get those via addons which was helpful when training new users because some people werenβt familiar enough w theirβ¦