We have been busy, too busy, upgrading our mail servers to SmarterMail v6.x for the last month.
First of first, I should thank SmarterTools for their great product, although we run into many troubles in SM 6.1 which is now solved in SM 6.5
Some new features in my opinion on SM 6.x:
- Better Spam Protection
- Use of Silverlight (Yep, they are using Silverlight for showing charts)
- Use of Telerik Controls (This has helped a lot to our users who were on slow connections, since Telerik controls load much fast than the ones used before)
- Integration with SpamAssassin is much more robust
All together, and add their ability to provide Hosted Mail Service, they are going great.