Missing some key features
I'm a loyal customer but your service is missing some key features.
Most importantly is the ability to upload multiple lists and combine them for future use. Having to compile various combinations of 100 or more subdivision lists myself in Excel is a pain. Most postcard websites already have this feature.
Less importantly, it would be nice to have separate users together on one account. I handle marketing for various individuals and it would be great to be able to see their order histories separately without danger of mixing up their credit card info.
Your customer service, printing quality, and UI are wonderful other than those gripes.