Here is an option.

OctoTools is an easy to use document management tool suite that encompasses
Forms Design, Report Formatting, Electronic Distribution, Printing, and Text
to PDF conversion.
Advanced features include GUI based design environment, Built-in Post Script
and PCL printer output, Drag and Drop placement of all elements, Automatic
dynamic text and forms merge, Text boxes for dynamic and static text & Data
Design elements, objects, images & text boxes, User defined "green bar" type
striping, "Watched" directory support, Conditional based data formatting,
Dynamic switch of overlays based on data, Barcodes including 2D pdf417,
Email, URL, or whole file, Multiprocessor support, Variable opacity of
elements and backgrounds, and more.
visit us at www.jbmsystems.com

Note: we can burst, pasword protect and email with our product that is very
well prices
for it's functionality and beats our major competitors.

If you run the following macro when a document produced by executing the
merge to a new document, it will send each of the 50+ letters to the printer
as a separate print job.  Therefore, if you can configure the printer to
take the first page of each print job from tray 3 and the following pages of
each print job from tray 2, you should get what you want.