Hey Doc, I have also had to look into this matter. We currently don't have any type of Exchange environment and I am not keen on Exchange because of cost and difficulty. For small clients its not worth it.

I have found this product, which I am going to trial and I will let you know how it works.
It may actually be just what you were looking for if you have not found anything yet. I quite like the product from what I have read.

If you have looked at it and dismissed this product as an option, I would be interested in hearing why.

http://www.altn.com/Products/

Ta Rob