I upload 1200x1800 @300dpi as part of my standard workflow. I sell/offer 1200x1800 digital downloads to my customers. This should be sufficient for printing decent size prints. However, it has been brought to my attention, by my customers, that the downloads are 1200x1800 @72dpi. I confirmed this by downloading a customer's order today.
I checked the compression level with imagemagic and it's a Quality of 95%. In this case my original file is 1.3mb @30dpi and the delivered image is 780k @72dpi.
This is completely unacceptable to have customers complain about quality when they take the file to a third-party and it prints out horrible. My only workaround is to email them the original file.