We have been using atMail as an internal tool since 2007 so it has grown up over time and does everything that it should be doing well. The design interface could use some improvement but considering it's not designed by us I think they are working hard enough to make improvements. It isn't easy finding something new that makes me wish I would go back to another provider! They were quick to implement my changes into their system when needed and also very helpful throughout this process. This was primarily so I could send important information internally without having to open a third party application. I have been using atmail since 2012 as an internal provider for my organization. They are very helpful and responsive! The interface could be improved a bit but overall it's great. Their platform has allowed us to continue growing while working remotely from home during this time. Nothing really. I would say that their pricing model might turn off some customers who prefer more traditional rates. We've used them for years now and they're always up there when needed.