[connortomas]

37 Signals generally create web apps for small businesses, so I suspect an email client/service would be a little too general for them. Jason Fried also says, "This new product eliminates the hassle of one thing in particular", which suggests that there's one huge pain point they'd like to solve with their new product. I can't think of what one particular pain point would be with email - a solution to email would probably involve solving a lot of tiny problems.

It's puzzling, because Jason points out that "the other products are totally free". Most web apps marketed to small business users, though, aren't free. Perhaps this product is targeted at a broader demographic.