If you have recently purchased a new HP printer and are unable to print letters from RezStream Professional, we have seen that some newer HP Printers will not work well with RezStream Professional. This is because HP has discontinued support for Post Script Drivers on their new printers, which RezStream Professional uses to print. HP has released a Universal Post Script Driver that you can download here, but that is not guaranteed to resolve the issue.
The first thing that you will want to try is changing the default printer in windows. To do this go to the start menu and select 'Devices and Printers'. Right click on a printer that is not the HP printer and select 'Set as default printer'. Once this is done try to print the same letter and it might be working.
If that does not work, another option would be to try printing to a PDF and then printing that PDF. Here are some instructions on setting up a PDF printer.
A third option would be to try using google cloud print, this requires an internet connection and a gmail account. This article explains how to use google cloud print.