I give it 4/5. I was in need of testing and wanted a free, thin, and lightweight email server that I could test with. I had it set up and working in about 20 minutes with no problems, whatsoever. It is pretty powerful for a FREE email server. I have used paid products that lack some features this offers and are harder to manage. It's no Exchange, but simple to use. Worked great for my test VM and I'd use it again in test.