Printing letters directly from your printer would definitely be an awesome idea however, there could be instances that some information may be included without prior notice. One of these is the Stash website link wherein it may be included as a footer to your letter.
Adjusting the print settings would be the solution to this. To know more on how to adjust and do this, just simply check out this article here for further information.
Should you require further assistance on how to do this, please do let us know and we'd be more than glad to assist you.