Hi,try this version
Dear xx,
It's been a long time since you placed the order with us last time, how's the business going
there?Are you making good profit by selling our new products?Or any problems you he in selling them?
We'd really appreciate that you could revert your feedbacks on the selling situation,it's not only good for us to help you solve the problems ifyou he,but more importantly,also good for us to perfect our products,and to he a better cooperation with you in the near[收起]